Question

se X - Y = 7 e XY = 60 , entao o valor de X² + Y² é?

Answer 1

{xy=60
{x-y=7

x=7+y
y(7+y)=60
7y+y²=60
y²+7y-60=0
(-7±√49-4*1*-60)/2
(-7±√49+240)/2
(-7±17)/2
y'=5
y''=-12

x=7+y
x=7-12=-5
x=7+5=12

x²+y²=
144+25=169
x²+y²=169