Question

qual o resposta da conta (x+7) (x-7) + 61 = 7x

Answer 1

(x+7) (x-7) + 61 = 7x

x² - 7x + 7x - 49 + 61 = 7x
x² + 12 = 7x
x² - 7x + 12 = 0

a = 1
b = -7
c = 12

Δ = b² -4 .a . c
Δ = (-7)² -4 . 1 . 12
Δ = 49 - 48
Δ = 1


$\mathtt{\dfrac{-b+-~\sqrt{\Delta}}{2~.~a}~~=~~\dfrac{-(-7)+-~\sqrt{1}}{2~~.~1}~~=~~\dfrac{7+-~1}{2}} \\ \\ \\ \mathtt{x' = \dfrac{7+1}{2}~~=~~\dfrac{8}{2}~~=~~4} \\ \\ \\ \mathtt{x'' = \dfrac{7-1}{2}~~=~~-\dfrac{6}{2}~~=~~3}$

Resposta: S{3 e 4}