Question

b的绝对值=3(b＜0）时,求下列算式的值

Answer 1

-b[(a-2b)的平方＋2b(a-2b)-(a＋2b)(a-2b)]除以(-2b)的平方

=-b(a^2-4ab+4b^2+2ab-4b^2-a^2-4b^2)/(4b^2)

=-b(-2ab-4b^2)/4b^2

=(2ab^2+4b^3)/4b^2

=a/2+b

因为a=-8 |b|=3 (