Question

八年级上册数学题目,帮忙啊!注：以上题目含次方的都是2次方.

Answer 1

(a²-b²)/ab-(ab-b²)/(ab-a²)

=(a²-b²)/ab-b(a-b)/a(b-a)

=(a²-b²)/ab+b/a

=(a²-b²+b²)/ab

=a²/ab

=a/b

1/a-1÷(a²-1)/(a²+a)

=(1-a)/a×a(a+1)/(a-1)(a+1)

=-1

[1-(a²+8)/(a²+4a+4)]÷(4a-4)/(a²+2a)

=(a²+4a+4-a²-8)/(a+2)²÷4(a-1)/a(a+2)

=4(a-1)/(a+2)²÷4(a-1)/a(a+2)

=a/(a+2)

[(2a-2b)/(a²-2ab+b²)+b/(a²-b²)]÷(3b+2a)/(a-b)

=[2(a-b)/(a-b)²+b/(a-b)(a+b)]÷(3b+2a)/(a-b)

=(2a+2b+b)/(a+b)÷(3b+2a)/(a-b)

=(a-b)/(a+b) a=5 b=2

=(5-2)/(5+2)

=3/7