Question

当a=-8,|b|=3时,求代数式-b[(a-2b)^2 +2b(a-2b)-(a+2b)(a-2b)]/(2b)^2的

Answer 1

-b[(a-2b)^2 +2b(a-2b)-(a+2b)(a-2b)]/(2b)^2

=-b(a-2b)(a-2b+2b-a-2b)/4b²

=-b(a-2b)*(-2b)/4b²

=(a-2b)/2

当a=-8,b=3

(a-2b)/2=(-8-6)/2=-7

当a=-8,b=-3

(a-2b)/2=(-8+6)/2=-1