Question

Observe a função dada pela lei f(x)= x ao quadrado +13x -7 com domínio real e determine o valor de x se f(x) = -7​

Answer 1

$f(x)~=\,-7\\\\\\x^2+13x-7~=\,-7\\\\\\x^2+13x-7+7~=~0\\\\\\x^2+13x~=~0~~~\rightarrow~~~Equacao~do~2^o~grau~incompleta\\\\\\x.(x+13)~=~0\\\\\\Solucao:\\\\\boxed{x'~=~0}\\\\ou\\\\x''+13~=~0\\\\\boxed{x''~=\,-13}$