Question

4x² + 9 = 12x:

A) x’ = 7/2; x” = –1/2
B) x’ = 9/4; x” = –3
C) x’ = –1/2; x” = –1/2
D) x = ∄

Answer 1

Resposta: D) x = ∄.

Explicação: 4x² + 9 = 12x

4x² - 12x + 9 = 0

sendo assim, a = 4, b = -12 e c = 9.

Δ = b² - 4.a.c

Δ = (-12)² - 4.4.9

Δ = + 144 - 144

Δ = 0

x = – b ± √Δ

——÷——

2.a

x = - (- 12) ± √0

———÷——–

2.4

x = 8 ± √0 x' = 8 + 0 = 8 x" = 8 - 0 = 8

——÷—— x' = 8 ÷ 8 x" = 8 ÷ 8

8 x' = 0 x" = 0