Question

Bài 2 tìm x biết :

a ) | x - 1 | = 5

b) x² = 25

c) 3 . ( x - 2 ) = 5 . ( x + 1 )

d) 3. x + 5⁹⁴ : 5⁹² = 3² + 8

Answer 1

a.|x-1|=5

=> hai TH

x-1=5 =>x=5+1=6

x-1=-5 => x= -5+1=-4

b. x² = 5²

=> x=5

Answer 2

a ) | x - 1 | = 5

+ x - 1 = 5 hoặc x -1 = -5 + x - 1 = 5 x = 5 + 1 x = 6 + x - 1 = -5 x = -5 + 1 x = -4 Vậy x = 6 hoặc x = -4 b, \(x^2=25\) \(x^2=5^2\) => x = 5 c) 3 . ( x - 2 ) = 5 . ( x + 1 ) 3x - 6 = 5x + 5 -5 - 6 = 5x - 3x -11 = 2x x = -11 : 2 x = \(\dfrac{-11}{2}\)

d) 3. x + 5\(^{94}\) : 5\(^{92}\) = 3\(^2\) + 8

3x + \(5^2\) = 9 + 8

3x + 25 = 17

3x = 17 - 25

3x = -8

x = -8 : 3

x = \(\dfrac{-8}{3}\)