Question

Determine a raíz da função:
a) x=x^-2x-15

Answer 1

$a) x^2-2x-15 \\ \\ x_{1\ y\ 2}= \dfrac{-b\pm \sqrt{b^2-4ac}}{2a} \qquad a= 1\quad b= -2\quad c= -15 \\ \\ \\ x_{1\ y\ 2}= \dfrac{-(-2)\pm \sqrt{(-2)-4(1)(-15)}}{2(1)}\\ \\ \\ x_{1\ y\ 2}= \dfrac{+2\pm \sqrt{4-(-60)}}{2}\\ \\ \\ x_{1\ y\ 2}= \dfrac{+2\pm \sqrt{4+60}}{2}\\ \\ \\ x_{1\ y\ 2}= \dfrac{+2\pm \sqrt{64}}{2}\\ \\ \\ x_{1\ y\ 2}= \dfrac{+2\pm8}{2} \\ \\ \\ x_1= \dfrac{2+8}{2}\qquad \qquad x_2= \dfrac{2-8}{2} \\ \\ \boxed{ \boxed{x_1= 5}\qquad \qquad \boxed{x_2= -3}}$