解方程,1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)我解的是无解额...
问题描述：
解方程,
1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)
我解的是无解额...
答
1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)
(x+6)(x+7)(x+8)+(x+5)(x+6)(x+7)=(x+5)(x+8)(x+7)+(x+5)(x+6))(x+8)
(x+8)(x+7)(x+6-x-5)=(x+5)(x+6)(x+8-x-7)
x2+15x+56=x2+11x+30
4x=-26
x=-13/2
那个x后面的2是平方啦，我打不出，你凑合看吧。
答
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