Question

解方程,1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)我解的是无解额...

Answer 1

1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)

(2x+13)/(x+5)(x+8)=(2x+13)/(x+6)(x+7)

(2x+13)(1/(x+5)(x+8)-1/(x+6)(x+7))=0

(2x+13)(-2/(x+5)(x+8)(x+6)(x+7))=0

2x+13=0

x=-13/2