1、B？ 2、C？ 3、D4，2

5、k=-4，{x=- 1？ Y=-3 is not the solution of this equation.

6{ 1}b= 16-4a/3？ {2} When a =-2,0 and 1, the corresponding values of b are 8,16/3,4 respectively.

Binary linear equations

1、A？ 2、D3、D4、8

5. Let the number of people going to Beijing be X and the number of people going to Emperor Island be Y. According to the meaning of the question, {X+Y = 128X = 2Y- 1.

Solving binary linear equations

1、D2、C3、A？ 4、2x=-4？ 5、①，y=-2x+3，②， 1， 1,{x= 1，y = 16 ,{ x = 2，y=- 17 ,{ x = 1，y =- 1

Communication and inquiry

The record is wrong. Reason: a toothbrush is X yuan, and a box of toothpaste is Y yuan. According to the meaning of the question, {39x+21y = 396,52x+28y = 518 is simplified, and this equation is {13x+7y = 132,13x+7y.

Test questions of binary linear equations [8. 1, 8.2]

1. 1，A2。 b？ 3.c？ 4.c？ 5.b？ 6.d？ 7.C8.B？ 9.A 10。 B

Two. 1 1.5，2 12.2[2x+y]= 10 13。 1/4? 14.？ 3-x/3，3-3y 15.23/2 16。 The answer is not unique, such as {x+y =- 1? x-y=3 17。 -4? 18? {x= 1？ y=3？ {x=2？ y= 1 19.9？ 20.{2x-3y= 16x+y= 1

3.2 1. From the meaning of the question, {2m+3 = 1, 5n-9 = 1, {m =- 1? n=2？ ∴m square +n square = [- 1] square +2 square =5.

22. In terms of meaning, {-2-3m = 7, -n+9 =-4? The solution is {m =-3? n= 13∴3m-4n=3x〔-3〕-4x 13=-6 1

Look at the picture below