Question

1.某同学在运算时误将A+B看成了A-B,求出的结果是-7x^2+9x+18,其中B为5x^2-4

Answer 1

1.A－B＝A－(5x^2-4)＝-7x^2+9x+18,A＝-7x^2+9x+18+ 5x^2-4＝-2x^2+9x+14

A+B＝-2x^2+9x+14+ 5x^2-4＝3x^2+9x+10

2.m^2-12m+2006＝4（2m^2-3m）+2006＝2002

3.－8a-2b+1=6.则8a+2b=-5,x=2代入,8a+2b+1=-4

4.a=-3、b=2代入得原式,原式＝180