Cái này làm gì phải lớp 6 - hình như lớp 8 mới đúng

(7x -11)³ - 200 = 2⁵. 5²

(7x - 11)³ - 200 = 32 . 25 

(7x - 11)³ - 200 = 800

(7x - 11)³ = 800 + 200

(7x - 11)³ = 1000

(7x -11)³ = 10³

7x - 11 = 10

7x = 10 + 11

7x = 21

x = 21: 7

x = 3

Vậy x=3 

bài lớp 6 đấy

ở đề cương ôn tập lớp 6

3^{x - 2} = 81

3^{x - 2} = 3⁴

=> x - 2 = 4

=> x = 4 + 2

=> x = 6

\(^{3^{x-2}=81}\)

\(\Rightarrow3^{x-2}=3^4\)

\(\Rightarrow x-2=4\)

\(\Rightarrow x=6\)

a)\(2.3^x=162\)

\(\Rightarrow3^x=162:2\)

\(\Rightarrow3^x=81\)

\(\Rightarrow3^x=3^4\)

=> x = 4

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

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

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

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

=> Không tìm được số tự nhiên x.

a) 2 x 3^x = 162

    3^x        = 162 : 2

    3^x        = 81

    3^x       = 3⁴

=> x = 4

b) (7x - 11)³ = 2⁵ x 5² + 200

    (7x - 11)³ = 32 x 25 + 200

    (7x - 11)³ = 800 + 200

    (7x - 11)³ = 1000

    (7x - 11)³ = 10³

=> 7x - 11 = 10

     7x       = 10 + 11

     7x       = 21

       x       = 21 : 7

       x       = 3

a)2x\(3^x\)=162

        3^x=162:2

        3^x=81

        3^x=3⁴

^{\(\Rightarrow\)x=4}

b)(7x-11)³=2⁵x5²+200

(7x-11)³=800+200

(7x-11)³=1000

(7x-11)³=10³

7x-11        =10

7x             =10+11

7x             =21

  x             =21:7

  x             =3

Chúc bạn học tốt !

( 7x - 11 )³ = 2⁵ . 5² + 200
\(\Rightarrow\)( 7x - 11 )³ = 32 . 25 + 200
\(\Rightarrow\)( 7x - 11 )³ = 800 + 200 
\(\Rightarrow\)( 7x - 11 )³ = 1000
\(\Rightarrow\)( 7x - 11 )³ = 10³
\(\Rightarrow\)7x - 11 = 10
\(\Rightarrow\)7x = 10 + 11 = 21
\(\Rightarrow\)x = 21 : 7
\(\Rightarrow\)x = 3

( 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

7x - 11 = 10

7x = 10 + 11

7x = 21

  x = 21 : 7

  x = 3

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

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

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

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

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

\(7x-11=10\)

\(7x=11+10\)

\(7x=21\)

\(x=21:3\)

\(x=7\)

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

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

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

\(x=\frac{10+11}{7}=3\)

**** cho mik nhé!

\(\left(7x-11\right)^3=2^5\times5^2+200\)

\(\Rightarrow\left(7x-11\right)^3=1000=10^3\)

\(\Rightarrow7x-11=10\)

\(7x=10+11\)

\(7x=21\)

\(x=21\div7\)

\(x=3\)

( 7x - 11 )³ = 2⁵ . 5² + 200

( 7x - 11 )³ = 32 . 25 + 200

( 7x - 11 )³ = 1000

( 7x - 11 )³ = 10³

7x - 11 = 10

7x = 10 + 11

7x = 21

  x = 21 : 7

  x = 3

720 : [41-(2x-5)] =2^3 . 5

<=> 41-(2x-5)=720:40=18

<=> 2x-5=41-18=23

<=>2x=23+5=28

<=> x=28:2=14

2^x-15=17

<=> 2^x=17+15=32

<=> 2^x=2^5

<=> x=5

(7x-11)^3= 2^5.5^2+200

<=> (7x-11)^3=1000

<=> (7x-11)^3=10^3

<=> 7x-11=10

<=> 7x=10+11=21

<=> x=21:7=3

2^x-15=17 nhe. Minh viet nham

3³ . 3^{2x - 1} = 81

3³ . 3^{2x - 1} = 3⁴

       3^{2x - 1} = 3⁴ : 3³ = 3

  => 2x - 1 = 1

          2x   = 2

            x   = 2 : 2 = 1