Question

Dada a função f(x)=x²-x-72, calcule suas raízes​

Answer 1

Explicação passo-a-passo:

$\sf x^2-x-72=0$

$\sf \Delta=(-1)^2-4\cdot1\cdot(-72)$

$\sf \Delta=1+288$

$\sf \Delta=289$

$\sf x=\dfrac{-(-1)\pm\sqrt{289}}{2\cdot1}=\dfrac{1\pm17}{2}$

$\sf x'=\dfrac{1+17}{2}~\Rightarrow~x'=\dfrac{18}{2}~\Rightarrow~x'=9$

$\sf x"=\dfrac{1-17}{2}~\Rightarrow~x"=\dfrac{-16}{2}~\Rightarrow~x"=-8$

As raízes são 9 e -8