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【329729】5.2 求解二元一次方程组 同步练习4

时间:2025-02-03 19:06:19 作者: 字数:1829字


 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

5.2 求解二元一次方程组

一、选择题

1.四名学生解二元一次方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> 提出四种不同的解法,其中解法不正确的是( )

A.由①得x= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> ,代入②

B.由①得y= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> ,代入②

C.由②得y= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> ,代入①

D.由②得x=3+2y,代入①

2.用代入法解方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> 使得代入后化简比较容易的变形是( )

A.由①得x= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> B.由①得y= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

C.由②得x= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> D.由②得y=2x5

3.用加减法解方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> 时,要使两个方程中同一未知数的系数相等或相反,有以下四种变形的结果:

 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

其中变形正确的是( )

A.①② B.③④ C.①③ D.②④

4.如果5x3m2n2ynm+11=0是二元一次方程,则( )

A.m=1,n=2 B.m=2,n=1

C.m=1,n=2 D.m=3,n=4

5.已知 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> xb+5y3a和-3x2ay24b是同类项,那么a,b的值是( )

A. <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> B. <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

C. <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> D. <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

二、填空题

6.x= <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> y1代入4x9y=8,可得到一元一次方程_______.

7.用代入法解方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> 由②得y=______③,把③代入①,得________,解得x=________,再把求得的x值代入②得,y=________.原方程组的解为_______.

8.关于x,y的方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> 中,若x的值为 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> ,则m=______,y=________.

9.2a7xyb17与- <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> a2b2x+3y是同类项,则x=________,y=________.

10.解关于x的方程组 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>m满足方程5x+8y=38时,m=____.

三、解答题

11.用代入法解下列方程组

1 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>



(2) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>



12.用加减法解方程组

(1) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>



(2) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>



13.在公式Sn=na1+ <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> d中,已知S2=5S4=14,求S6的值.



14.解方程 <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> .




参考答案

一、1.C 2.D 3.B 4.D 5.D

二、6.5x+4=0

7.4x1,x+2(4x1)=7,1,3, <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

8. 2,1

9. 1,5

10. <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> ,2

三、11.(1) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> (2) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

12.(1) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a> (2) <a href="/tags/48/" title="练习" class="c1" target="_blank">练习</a> <a href="/tags/50/" title="同步" class="c1" target="_blank">同步</a> <a href="/tags/380/" title="方程" class="c1" target="_blank">方程</a>

13.S6=27

14.(6,5,3)