Question

Tìm x biết :

a)  1999^{2x - 6} = 1 

b)  2^x x 4 = 128

c)  ( 2x + 1 ) ³ = 125

Answer 1

a)  1999^{2x - 6} = 1 

1999^{2x - 6} = 1999⁰

=>2x-6=0

2x=0+6

2x=6

x=6:2

x=3

b)  2^x x 4 = 128

2^x=128:4

2^x=32

2^x=2⁵

=>x=5

c)  ( 2x + 1 ) ³ = 125

( 2x + 1 ) ³ = 5³

2x+1=5

2x=5-1

2x=4

x=4:2

x=2

Answer 2

a)1999^2x-6=1

1999^2x-6=1999⁰

=>2x-6=0

2x=0+6

2x=6

x=6:2

x=3

b)2^x.4=128

2x=128:4

2x=32

x=32:2

x=5

c)(2x+1)³=125

(2x+1)³=5³

2x+1=5

2x=5-1

2x=4

x=4:2

x=2

Answer 3

a , x= 3                                       b , x = 5                                               c , x = 2

Answer 4

a)    x=3

b)    x=5

c)    x=2