Question

[Lê Bùi Thiên Kim Bảo]

Ai làm giúp tui 

Answer 1

[Ga'l wes]

a ) 2 . 3^x = 162

3^x = 162 : 2

3^x = 81

3^x = 3⁴

\(\Rightarrow\)x = 4

Vậy x = 4

b ) 2^x - 15 = 17

2^x = 17 + 15

2^x = 32

2^x = 2⁵

\(\Rightarrow\)x = 5

Vậy x = 5

c ) ( 7x - 11 )³ = 2⁵ . 5² + 200

( 7x - 11 )³ =  32 . 25 + 200

( 7x - 11 )³ = 800 + 200

( 7x - 11 )³ = 1000

( 7x - 11 )³ = 10³

\(\Rightarrow\)7x - 11 = 10

\(\Rightarrow\)7x = 21

\(\Rightarrow\)x = 3

Vậy x = 3

d ) 64 . 4^x = 4⁵

4³ . 4^x = 4⁵

4^x = 4⁵ : 4³

4^x = 4²

\(\Rightarrow\)x = 2

Vậy x = 2

e ) 49 .7^x = 2401

7² . 7^x = 7⁴

7^x = 7⁴ : 7²

7^x = 7²

\(\Rightarrow\)x = 2

Vậy x = 2

Answer 2

[Lê Minh Vũ]

\(a)\)\(2.3^x=162\)

\(\Rightarrow\)\(3^x=162\div2\)

\(\Rightarrow\)\(3^x=81\)

\(\Rightarrow\)\(3^x=3^4\)

\(\Rightarrow\)\(x=4\)

\(b)\)\(2^x-15=17\)

\(\Rightarrow\)\(2^x=17+15\)

\(\Rightarrow\)\(2^x=32\)

\(\Rightarrow\)\(2^x=2^5\)

\(\Rightarrow\)\(x=5\)

\(c)\)\(\left(7x-11\right)^3=2^5.5^2+200\)

\(\Rightarrow\)\(\left(7x-11\right)^3=32.25+200\)

\(\Rightarrow\)\(\left(7x-11\right)^3=800+200\)

\(\Rightarrow\)\(\left(7x-11\right)^3=1000\)

\(\Rightarrow\)\(\left(7x-11\right)^3=10^3\)

\(\Rightarrow\)\(7x-11=10\)

\(\Rightarrow\)\(7x=10+11\)

\(\Rightarrow\)\(7x=21\)

\(\Rightarrow\)\(x=3\)

\(d)\)\(64.4^x=4^5\)

\(\Rightarrow\)\(64.4^x=1024\)

\(\Rightarrow\)\(4^x=1024\div64\)

\(\Rightarrow\)\(4^x=16\)

\(\Rightarrow\)\(4^x=4^2\)

\(\Rightarrow\)\(x=2\)

\(e)\)\(49.7^x=2401\)

\(\Rightarrow\)\(7^x=2401\div49\)

\(\Rightarrow\)\(7^x=49\)

\(\Rightarrow\)\(7^x=7^2\)

\(\Rightarrow\)\(x=2\)