几道数学题啊`不够再加

一般这种的最好要先化简，再求值，这样比较不容易计算错
1、[4ab/a-b +(a/b - b/a)÷(1/a + 1/b)]÷(a^2+2ab+b^2)
={4ab/a-b +[(a^2-b^2)/ab]*ab/(a+b)}*1/(a+b)^2
=(a+b)^2/(a-b)*1/(a+b)^2
=1/(a-b)
=1/3
2、[(a/b - b/a)÷(a+b)+a(1/b - 1/a)]÷1+a/b
=[(a-b)/ab+a(a-b)/ab]*[b/(1+a)]
=[(a-b)(a+1)/ab]*[b/(1+a)]
=a-b
=1/6
3、(x/y - y/x)÷(x/y + y/x -2)÷x/x-y
=[(x+y)(x-y)/xy]*[xy/(x^2-y^2)]*(x-y)/x
=(x-y)/x
=1-y/x

[4ab/a-b +(a/b - b/a)÷(1/a + 1/b)]÷(a^2+2ab+b^2)
=[4ab/(a-b) + (a^2-b^2)/a+b] ÷ (a+b)^2
=[4ab/(a-b) + a-b] ÷ (a+b)^2
=[4*2*(-1)/3 + 3]/1^2
=1/3

[(a/b - b/a)÷(a+b)+a(1/b - 1/a)]÷(1+a/b)
=[(a^2-b^2)/(ab)/(a+b)+(a-b)/b]*(a+b)/b
=[(a-b)/ab+(a-b)/b]*(a+b)/b
=[1/6*6+1/6*3]*(5/6)*3
=15/4

(x/y - y/x)÷(x/y + y/x -2)÷x/x-y
=(x^2-y^2)/(x^2+y^2-2xy)*(x-y)/x
=(x+y)(x-y)/(x-y)^2*(x-y)/x
=(x+y)/x
=1+y/x

要先化简，再求值
1、[4ab/a-b +(a/b - b/a)÷(1/a + 1/b)]÷(