Salut tout le monde jai besoin daide lapplication 8 SVP =)

Bonjour,
a>0, b>0, a>0, y>0
[tex]\dfrac{x}{y}<\dfrac{ax+by}{bx+ay}\\\\<=>x(bx+ay)<y(ax+by)\\ \\<=> bx^2+axy-axy-by^2<0\\ \\<=>b(x^2-y^2)<0\\\\<=> (x-y)(x+y)<0\\ \\<=>x-y<0\\\\<=>x<y\\ \\<=>\dfrac{x}{y}<1[/tex]
Merci