Question

Quais os zeros da função f(x) = x² +x -6 *

A) -2 e 3

(B) 2 e -3

(C) -2 e -3

(D) 2 e 3

(E) 0 e 1​

Answer 1

x² + x - 6 = 0

∆ = 1² - 4. 1. (-6)

∆ = 1 + 24

∆ = 25

x = -1 ± √25/2.1

x = -1 ± 5/2

x' = -1 + 5 = 4/2 = 2

x" = - 1 - 5 = - 6/2 = - 3

Alternativa b) 2 e -3

Answer 2

Explicação passo-a-passo:

$\sf x^2+x-6=0$

$\sf \Delta=1^2-4\cdot1\cdot(-6)$

$\sf \Delta=1+24$

$\sf \Delta=25$

$\sf x=\dfrac{-1\pm\sqrt{25}}{2\cdot1}=\dfrac{-1\pm5}{2}$

$\sf x'=\dfrac{-1+5}{2}~\Rightarrow~x'=\dfrac{4}{2}~\Rightarrow~\red{x'=2}$

$\sf x"=\dfrac{-1-5}{2}~\Rightarrow~x"=\dfrac{-6}{2}~\Rightarrow~\red{x"=-3}$

Os zeros dessa função são $\sf 2~e~-3$

Letra B