2xy+y²=15 !x-y!=6 1/ x-y=6 x>y x=y+6 2(y+6)y+y²=15 2y²+12y+y²=15 y²+4y-5=0 D=16+20=36 y12=(-4+-6)/2=-5 1 y=1 x=7 y=-5 x=1 2/ x-y=-6 xx=y-6 2(y-6)y+y²=15 2y²-12y+y²=15 3y²-12y-15=0 y²-4y-5=0 D=36 y12=(4+-6)/2=5 -1 y=5 x=-1 y=-1 x=-7