Question

A soma de um número com seu quadradro é 30.calcule esse numero.

Answer 1

x² + x = 30

x² + x - 30 = 0

a = 1

b = 1

c = -30

Δ = b² - 4 .a . c

Δ = 1² - 4 . 1 . (-30)

Δ = 1 + 120

Δ = 121

$\mathtt{\dfrac{-b+-~\sqrt{\Delta}}{2~.~a} ~~=~~\dfrac{-1 +-~\sqrt{121}}{2~.~1}~~=~~\dfrac{-1 +-~11}{2}} \\ \\ \\ \mathtt{x' =\dfrac{-1+11}{2}~~=~~\dfrac{10}{2}~~=~~5} \\ \\ \\ \mathtt{x = \dfrac{-1 -11}{2}~~=~~-\dfrac{12}{2}~~=~~ - 6}$

Resposta: S{ -6 e 5 }