Question

se xy e igual20 e x-y e igual 8, qual e o valor de x2 menos xy2

Answer 1

$x.y=20\\ x-y=8\\\\ x=y+8\\ (y+8).(y)=20\\ y^2+8y-20=0\\ \Delta=8^2-4.1.(-20)=64+80=144\\\\ y=\frac{-8\pm\sqrt{144}}{2}\\\\ y_1=\frac{-8+12}{2}=2 \ \implies x_1=10\\\\ y_2=\frac{-8-12}{2}=-10 \ \implies x_2=-2\\\\ Possibilidade \ 1:\\ x^2-xy^2=(10)^2-(10).(2)^2=100-40=60\\\\ Possibilidade \ 2:\\ x^2-xy^2=(-2)^2-(-2).(-10)^2=4+2.100=4+200=204$