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【349986】-学年湖南省常德市七年级下学期期中考试数学试题含答案

时间:2025-03-05 22:10:52 作者: 字数:8615字
简介:

上学期期中考试

七年级 数学科目

(时量:120分钟 总分:120分)

一、选择题:(3*8=24分)

1.下列多项式中,含有因式 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 的多项式是(

A <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> B <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

C <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> D <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

2. 已知多项式 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 分解因式为 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> ,则 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 的值为(

A <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> B <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> C <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> D <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

3. 下列方程中,是二元一次方程的有(    )

A <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>   B <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>   C <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>  Dmn+m=7[来源:学科网]

4. 下列多项式乘法,能用平方差公式进行计算的是(      )

A.(x+y)(xy) B.(2x+3y)(2x3z)

C.(ab)(ab) D.(mn)(nm)

5. 下列多项式:①16x5-x;②(x-1)2-4(x-1)+4;③(x+1)4-4x(x+1) <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 2+4x2;④-4x2-1+4x分解因式后,结果含有相同因式的是(    )

(A)①④ (B)②④ (C)③④ (D)②③

6.  <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> ,则mk的值分别是(    )

Am=—2k=6Bm=2k=12Cm=—4k=—12D m=4k=-12

7.下列计算中,正确的是(  )

A.(a+b2=a2+b2 B.(ab2=a2b <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 2

C.(a+m)(b+n=ab+mn D.(m+n)(m+n=m2+n2

8下列分解因式正确的是  

A100p225q2=10+5q)(105q Bx2+x6=x+3)(x2

C4m2n2=2m+n)(2mn D <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

二、填空题:(3*8=24

9. 已知x+y=6xy=4x2y+xy2的值为     .

10多项式x2y(ab)xy(ba)y(ab)提公因式后另一个因式为_____________

11. 已知 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> ,则 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 的值是

12已知 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 是方程2x+ay=5的解,则 a=

13如果3x3m﹣2﹣2y2+n+10=0是二元一次方程,那么mn=   

14已知m2n26m10n340,则mn    

15如果xy满足方程组那么x2y2    

16 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 是完全平方公式,则m=         

三、解答题(72)

17(8)解下列方程组:

(1) ( 2)




18(8)分解因式:

(1)a3a (2)8(x22y2)x(7xy)xy.




19(8)已知|3x﹣2y+5|+3x﹣5y+22=0,求(xy22的值

20(8)已知二次三项式x2pxq的常数项与(x1)(x9)的常数项相同,而它的一次项与(x2)(x4)的一次项相同,试将此多项式因式分解.







21(10)先化简,再求值:

(1)(1a)(1a)(a2)2,其中a=;

(2)(2x <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 3)(2x3)4x(x1)(x2)2,其中x=-3.







22(10)已知方程组甲由于看错了方程①中的a,得到方程组的解为乙由于看错了方程②中的b,得到方程组的解为若按正确的ab计算,求原方程组的解.



23(10)为建设资源节约型、环境友好型社会,克服因干旱而造成的电力紧张困难,切实做好节能减排工作.某地决定对居民家庭用电实行“阶梯电价”,电力公司规定:居民家庭每月用电量在80千瓦时以下(80千瓦时,1千瓦时俗称1)时,实行“基本电价”;当居民家庭月用电量超过80千瓦时时,超过部分实行“提高电价”.

(1)小张家今年2月份用电100千瓦时,上缴电费68元;5月份用电120千瓦时,上缴电费88元.求“基本电价”和“提高电价”分别为多少元/千瓦时;

(2)6月份小张家预计用电130千瓦时,请预算小张家6月份应上缴的电费.





24(10)观察下列各式:

(x1)(x1)x21

(x1)(x2x1)x3 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 1

(x1)(x3x2x1)x41

(1)据以上规律,可知(x1)(x6x5x4x3x2x1)________

(2)你能否由此归纳出一般性规律:(x1)(xnxn1+…+x1)________

(3)根据(2)计算:1222+…+234235.




[来源:..]


座位号



组合 27 德上学期期中考试

七年级 数学科目 答卷

  1. 选择题(3*8=24分)


题号

1

2

3

4

5

6

7

8

答案









二、填空题:(3*8=24分)

9 10 11 12



13 14  <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 15 16  <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>


三、解答题(72)

17(8)解下列方程组:

(1) ( 2)






18(8)分解因式:

(1)a3a (2)8(x22y2)x(7xy)xy.



[来源:学科网]



19(8)已知|3x﹣2y+5|+3x﹣5y+22=0,求(xy22的值


[来源:§§Z§X§X§K]








20(8)已知二次三项式x2pxq的常数项与(x1)(x9)的常数项相同,而它的一次项与(x2)(x4)的一次项相同,试将此多项式因式分解.











21(10)先化简,再求值:

(1)(1a)(1a)(a2)2,其中a=;

(2)(2x3)(2x3)4x(x1)(x2)2,其中x=-3.




[来源:Z,xx,k.Com]





22(10)已知方程组甲由于看错了方程①中的a,得到方程组的解为乙由于看错了方程②中的b,得到方程组的解为若按正确的ab计算,求原方程组的解.









23(10)为建设资源节约型、环境友好型社会,克服因干旱而造成的电力紧张困难,切实做好节能减排工作.某地决定对居民家庭用电实行“阶梯电价”,电力公司规定:居民家庭每月用电量在80千瓦时以下(80千瓦时,1 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 千瓦 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 时俗称1)时,实行“基本电价”;当居民家庭月用电量超过80千瓦时时,超过部分实行“提高电价”. <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

(1)小张家今年2月份用电100千瓦时,上缴电费68元;5月份用电120千瓦时,上缴电费88元.求“基本电 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 价”和“提高电价”分别为多少元/千瓦时;

(2)6月份小张家预计用电130千瓦时,请预算小张家6月份应上缴的电费.





24(10)观察下列各式:

(x1)(x1)x2 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 1

(x1)(x2x1)x31

(x1)(x3x2x1)x41

(1)据以上规律,可知(x1)(x6x5x4x3x2x1)________

(2)你能否由此归纳出一般性规律:(x1)(xnxn1+…+x1)________

(3)根据(2)计算:1222+…+234235.






参考答案:CDCCADDB

924 10 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> X2+X+1 117 121 13-1 14-2 157-1 162

17.解:(1)+②,得6x12,解得x2.(2)x2代入①中,得23y8,解得y2.方程组的解为(4)

(2)原方程组可化为将①代入②中,得2(3y3)y4,解得y2.(6)y2代入①中,得x3.方程组的解为(8)

18.解:(1)原式=a(a21)a(a1)(a1)(4)

(2)原式=8x216y27x2xyxyx216y2(x4y)(x4y)(8)

19解:|3x2y+5|+3x5y+22=0

3x2 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> y+5=03x5y+2=0[来源:++Z+X+X+K]

 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> 解得: <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

xy22=[(﹣ <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>×(﹣12]2= <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>

20.解:(x1)(x9)x210x9,∴q9(2)(x2)(x4)x26x8,∴p=-6.(4)原二次三项式是x26x9.(6)因式分解,得x26x9(x3)2.(8)

21.解:(1)原式 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a>1a2a24a4=-4a5.(3)a=时,原式=-4×53.(5)

(2)原式=4x294x24 <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/51/" title="试题" class="c1" target="_blank">试题</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/208/" title="学期" class="c1" target="_blank">学期</a> <a href="/tags/255/" title="学年" class="c1" target="_blank">学年</a> <a href="/tags/261/" title="考试" class="c1" target="_blank">考试</a> xx24x4x25.(8)x=-3时,原式=(3)254.(10)

22.解:将代入②,得-12b=-2,∴b10.(3)将代入①,得5a2015,∴a=-1.(6)故原方程组为(8)解得(10)

23.解:(1)设“基本电价”为x/千瓦时,“提高电价”为y/千瓦时,(1)根据题意得

(3)解得(4)

答:“基本电价”为0.6/千瓦时,“提高电价”为1/千瓦时.(7)

(2)80×0.6(13080)×198()(9)

答:预计小张家6月份应上缴的电费为98元.(10)

24.解:(1)x71(3)

(2)xn11(6)

(3)原式=(21)(1222+…+234235)2361.(10)


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