Question

15题：已知a+b=-5,2a-b=-1,求ab(b+b²）-b²(ab-a)+2a(a-b&sup

Answer 1

15,a=-2 b=-3

ab(b+b^2）-b^2(ab-a)+2a(a-b^2）=ab^2+ab^3-ab^3+ab^2+2a^2-2ab^2=2a^2=2*(-2)^2=8;

16,（ax^2+bx+1)(2x^2-3x-1）=2ax^4+(2b-3a)x^3+(2-3b-a)x^2+(-3-b)x-1

不含x^3次项和x项可知2b-3a=0,-3-b=0,得 b=-3,a=-2