Question

(a-3ab+b) / (2a+2b-7ab)  =  1/3

Answer 1

(a-3ab+b) / (2a+2b-7ab) = 1/3

左边分子分母同除以ab

(1/b-3+1/a)/(2/b+2/a-7)=1/3

[(1/a+1/b)-3]/[2(1/a+1/b)-7]=1/3

令x=1/a+1/b

(x-3)/(2x-7)=1/3

3(x-3)=1*(2x-7)

3x-9=2x-7

x=2

1/a+1/b=2