Question

03) Se x + y = 8 e x – y = 5. Qual é o valor de x² + 6xy + y²?​

Answer 1

$x^2+6xy+y^2=?$

$\left \{ {{x+y=8} \atop {x-y=5}} \right. <=>$

$<=>\left \{ {{x=8-y} \atop {8-y-y=5}} \right. <=>$

$<=>\left \{ {{x=8-y} \atop {-2y=-3}} \right.<= >$

$<=>\left \{ {{x=8-\frac{3}{2} } \atop {x=\frac{3}{2} }} \right.<=>$

$<=>\left \{ {{x=\frac{13}{2} } \atop {y=\frac{3}{2} }} \right.$

$x^2+6xy+y^2=$

$=\frac{169}{4}+6*\frac{13}{2} *\frac{3}{2} +\frac{9}{4} =$

$=\frac{178+234}{4} =$

$=103$