Question

x+y=11
xy=24
x^2+y^2=?

Answer 1

x+y=S
xy=P
$x^{2} + y^{2} = S^{2} -2P= 11^{2} -2*24=121-48=73$
M-am folosit de relatiile lui Viete

Answer 2

(x+y)^2 = x^2 +2xy +y^2  => 11^2 = x^2 + 2xy +y^2 .
121 = x^2 + 2 *24 + y^2
121 = x^2 + 48+y^2
121 - 48= x^2+ y^2
73 = x^2 + y^2