Question

alguém me ajuda preciso entregar hoje por favor eu tô muito triste ​

Answer 1

Explicação passo-a-passo:

a)

$\sf x^2-x-12=0$

$\sf \Delta=(-1)^2-4\cdot1\cdot(-12)$

$\sf \Delta=1+48$

$\sf \Delta=49$

$\sf x=\dfrac{-(-1)\pm\sqrt{49}}{2\cdot1}=\dfrac{1\pm7}{2}$

$\sf x'=\dfrac{1+7}{2}~\rightarrow~x'=\dfrac{8}{2}~\rightarrow~\red{x'=4}$

$\sf x"=\dfrac{1-7}{2}~\rightarrow~x"=\dfrac{-6}{2}~\rightarrow~\red{x"=-3}$

b)

$\sf 2x^2-3x-5=0$

$\sf \Delta=(-3)^2-4\cdot2\cdot(-5)$

$\sf \Delta=9+40$

$\sf \Delta=49$

$\sf x=\dfrac{-(-3)\pm\sqrt{49}}{2\cdot2}=\dfrac{3\pm7}{4}$

$\sf x'=\dfrac{3+7}{4}~\rightarrow~x'=\dfrac{10}{4}~\rightarrow~\red{x'=\dfrac{5}{2}}$

$\sf x"=\dfrac{3-7}{4}~\rightarrow~x"=\dfrac{-4}{4}~\rightarrow~\red{x"=-1}$