1/x-1/(x+5)=1/10
10x+50-10x=x²+5x
x²+5x-50=0
x²+2*5/2x+25/4=50-25/4=175/4
(x+5/2)²=25/4*7
x+5/2=±5/2√7
x=±5/2√7-5/2