(7x-10)/(5x-17)>=(25x+50)/(10x²-49x+51)
(7x-10)/(5x-17)>=(25(x+2))/((2x-3)(5x-17))
((7x-10)(2x-3)-25(x+2))/((2x-3)(5x-17))>=0
(14x²-66x-20)/((2x-3)(5x-17))>=0
((7x+2)(2x-10))/((2x-3)(5x-17))>=0
on effectue un tableau de signes
donc S=]-inf;-2/7] U ]3/2;17/5[ U [5;+inf[