Question

Qual o resultado dessa expressão? x ( x + 4 ) + x ( x + 2 ) = 2 x /2 + 12

Answer 1

$x(x+4) + x(x+2) = \frac{2x}{2}+12\\\\ x^2+4x + x^2+2x = \frac{\not2x}{\not2}+12\\ 2x^2+6x -x -12 = 0\\\\ 2x^2+5x-12=0$

Encontrando as raízes utilizando fórmula de Bháskara:
$Termos:\ \ \ \ a=2\ \ \ \ b=5\ \ \ \ c=-12\\\\\\ x=\dfrac{-b\pm\sqrt{b^2-4.a.c}}{2.a}\\\\ x=\dfrac{-5\pm\sqrt{25+96}}{4}\\\\ x=\dfrac{-5\pm\sqrt{121}}{4}\\\\ x=\dfrac{-5\pm11}{4}\\\\\\ x'=\dfrac{-5+11}{4} =\dfrac{6}{4}=\boxed{\dfrac{3}{2}}\\\\\\ x''=\dfrac{-5-11}{4} =\dfrac{-16}{4}=\boxed{-4}$

Bons estudos!