Question

tìm x biết :

a) ( 5.x - 1 ) : 3 + 1 = 4

b) 54 : ( 16 - x ) - 1 = 5

c) 3^2 . x + 15 = 60

d)2x^3 = 54

e) 2^x+1 = 64

Answer 1

a) (5x - 1) : 3 + 1 = 4

=> (5x - 1) : 3 = 3

=> (5x - 1) = 9

=> 5x - 1 = 9

=> 5x = 10

=> x = 2

Answer 2

b) 54 : (16 - x) - 1=5

=> 54:(16-x) = 6

=> 16-x = 9

=> x = 7

Answer 3

c) 3² . x + 15 = 60

=> 9 . x + 15 = 60

=> 9 . x = 60 - 15

=> 9 . x = 45

=> x = 45 : 9

=> x = 5

Vậy x = 5

Answer 4

e) 2^x+1=64

=>2^x+1=2⁶

=> x+1=6

=>x=5

d) 2x³=54

=> x³=54:2

=> x³=27

=> x³=3³

=>x=3

Answer 5

ai làm câu c) 3^2 . x + 15 = 60 đi

Answer 6

a) (5x - 1) : 3 + 1 = 4

=> (5x - 1) : 3 = 4 - 1

=> (5x - 1) : 3 = 3

=> 5x - 1 = 3.3

=> 5x - 1 = 9

=> 5x = 9 + 1

=> 5x = 10

=> x = \(\dfrac{10}{2}=2\)

b) 54 : (16 - x) - 1 = 5

=> 54 : (16 - x) = 5 + 1

=> 54 : (16 - x) = 6

=> 16 - x = \(\dfrac{54}{6}\)

=> 16 - x = 9

=> x = 16 - 9 = 7

c) 3² . x + 15 = 60

=> 9x + 15 = 60

=> 9x = 60 -15

=> 9x = 45

=> x = \(\dfrac{45}{9}=5\)

d)2x³ = 54

=> x³ = \(\dfrac{54}{2}\)

=> x³ = 27

=> x = \(\sqrt{27}=3\)

e) 2^x+1 = 64

=> 2^x+1 = 2⁶

=> x + 1 = 6

=> x = 6 - 1 = 5