Question

x-y=9
xy=10, x²+y²=?

Answer 1

$(x-y)^2=9^2$
$x^2-2xy+y^2=81$
$x^{2} -2*10+y^2=81$
[tex] x^{2} -20+y^2=81 [/tex]
$x^{2} +y^2=81+20$
$x^{2} +y^2=101$