Question

Se x^2+y^2= 51 e xy = 48, o valor de (x + y)^2 é

159

123

147

162​

Answer 1

$\Large\boxed{\begin{array}{l}\tt dados\begin{cases}\sf x^2+y^2=51\\\sf x\cdot y=48\\\sf (x+y)^2=?\end{cases}\\\underline{\rm soluc_{\!\!,}\tilde ao\!:}\\\sf (x+y)^2=x^2+y^2+2\cdot x\cdot y\\\sf (x+y)^2=51+2\cdot48\\\sf (x+y)^2=51+96\\\sf (x+y)^2=147\end{array}}$