数学题2x/(x-7)加x-7/2x等于2 求x的解

令2x/(x-7)=a
则(x-7)/2x=1/a
a+1/a=2
a²+1=2a
a²-2a+1=(a-1)²=0
a=1
2x/(x-7)=1
2x=x-7
x=-7