计算：(a/a+b - b/b-a - 2ab/a^2-b^2)÷(1/a-1/b) 解方程：5/x+1 - 4/x =0 2-x/x-3 =1- 1/3-x 5/x-1=3/x
问题描述：
计算：(a/a+b - b/b-a - 2ab/a^2-b^2)÷(1/a-1/b) 解方程：5/x+1 - 4/x =0 2-x/x-3 =1- 1/3-x 5/x-1=3/x
5/x+1 - 4/x =0
2-x/x-3 =1- 1/3-x
5/x-1=3/x+1
答
(a/a+b - b/b-a - 2ab/a^2-b^2)÷(1/a-1/b)=[a*(a-b)+b*(a+b)-2ab)]/[(a+b)(a-b)]*(ab)/(b-a)=(a-b)/(a+b)*(ab)/(b-a)=-ab/(a+b)5/(x+1) - 4/x =0(5x-4x-4)/[x(x+1)]=0x=4 代入x(x+1)＝20≠0 成立(2-x)/(x-3) =1- 1/...