Question

tìm x 

(3x-1)^3=-8/27

x^3/3=9

x^10=25.x^8

giúp mình nhé

Answer 1

(3x - 1)³ = -8/27

=> (3x - 1)³ = (-2/3)³

=> 3x - 1 = -2/3

=> 3x = -2/3 + 1

=> 3x = 1/3

=> x = 1/3 : 3

=> x = 1/9

x³ : 3 = 9

=> x³ = 9.3

=> x³ = 27

=> x³ = 3³

=> x = 3

x¹⁰ = 25.x⁸

=> x¹⁰ : x⁸ = 25

=> x^10-8 = 25

=> x² = 5² = (-5)²

=> x = 5 hoặc x = -5

Vậy x \(\in\){-5; 5}.

Answer 2

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)