Question

tìm x:

2^x . 4 = 128

( 2x + 1 ) ³ = 125

giải giúp mk nha

Answer 1

\(2^x.4=128.\)

\(2^x=128:4.\)

\(2^x=32.\)

\(2^x=2^5\Rightarrow x=5\in N.\)

Vậy \(x=5.\)

\(\left(2x+1\right)^3=125.\)

\(\left(2x+1\right)^3=5^3.\)

\(\Rightarrow2x+1=5.\)

\(\Leftrightarrow2x=4.\)

\(\Leftrightarrow x=4:2=2\in N.\)

Vậy \(x=2.\)

Answer 2

a) \(2^x.4=128\)

\(2^x=128:4\)

\(2^x=32\)

\(2^x=2^5\)

\(\Leftrightarrow x=5\left(tm\right)\)

Vậy ...................

b) \(\left(2x+1\right)^3=125\)

\(\left(2x+1\right)^3=5^3\)

\(\Leftrightarrow2x+1=5\)

\(\Leftrightarrow2x=4\)

\(\Leftrightarrow x=2\left(tm\right)\)

Vậy ..............

Answer 3

2^x . 4 = 128

2^x =128 : 4

2^x = 32

2^x = 2⁵

=> x = 5

( 2x + 1 )³ = 125

( 2x + 1)³ = 5³

=> 2x + 1 = 5

=> 2x = 5 -1

=> 2x = 4

=> x = 2