(7x - 11)³ = 2⁵.5² + 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 = 3

3^x + 25 = 26.2² + 2.3⁰

=> 3^x + 25 = 104 + 2

=> 3^x + 25 = 106

=> 3^x = 106 - 25

=> 3^x = 81

=> 3^x = 3⁴

=> x = 4

a)\(\left(7x-11\right)^3=2^5.5^2+200\)                                            b)  \(3^x+25=26.2^2+2.3^0\)

\(\left(7x-11\right)^3=32.25+200\)                                                   \(3^x+25=26.4+2.1\)

\(\left(7x-11\right)^3=800+200\)                                                        \(3^x+25=104+2\)

\(\left(7x-11\right)^3=1000\)                                                                   \(3^x+25=106\)

\(\Rightarrow\left(7x-11\right)^3=10^3\)                                                                  \(3^x=106-25\)

\(\Rightarrow7x-11=10\)                                                                            \(3^x=81\)

      \(7x=10+11\)                                                                            \(3^x=3^4\)      

        \(x=\frac{21}{7}\)                                                                                    \(\Rightarrow x=4\)

        \(x=3\)                                                                                      Vậy x = 4

Vậy x = 3

Giải:

\(a,2^x-15=17.\)

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

\(2^x=32.\)

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

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

Vậy \(x=5.\)

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

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

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

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

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

\(\Rightarrow7x-11=10.\)

\(\Rightarrow7x=10+11=21.\)

\(\Rightarrow x=21:7=3\in N.\)

Vậy \(x=3.\)

\(c,3^x+25=26.2^2+2.3^0.\)

\(3^x+25=26.2^2+2.1.\)

\(3^x+25=2\left(26.2+1\right).\)

\(3^x+25=2.53.\)

\(3^x+25=106.\)

\(3^x=106-25.\)

\(3^x=81.\)

\(3^x=3^4\Rightarrow x=4\in N.\)

Vậy \(x=4.\)

\(d,49.7^x=2041.\)(đề này sai).

Sửa đề:

\(49.7^x=2401.\)

\(7^x=2401:49.\)

\(7^x=49.\)

\(7^x=7^2\Rightarrow x=2\in N.\)

Vậy \(x=2.\)

\(e,3^x=243.\)

\(3^x=3^5\Rightarrow x=5\in N.\)

Vậy \(x=5.\)

~ Học tốt!!! ~

a, \(2^x-15=17\)

\(\Rightarrow2^x=32\Rightarrow2^x=2^5\)

Vì \(2\ne-1;2\ne0;2\ne1\) nên \(x=5\)

Vậy....

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

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

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

\(\Rightarrow7x-11=10\Rightarrow7x=21\Rightarrow x=3\)

Vậy.....

c, \(3^x+25=26.2^2+2.3^0\)

\(\Rightarrow3^x+25=26.4+2\)

\(\Rightarrow3^x=104+2-25\)

\(\Rightarrow3^x=81=3^4\)

Vì \(3\ne-1;3\ne0;3\ne1\) nên x=4

Vậy.....

d,Sửa đề:\(49.7^x=2401\)

\(\Rightarrow7^2.7^x=7^4\Rightarrow7^{2+x}=7^4\)

Vì \(7\ne-1;7\ne0;7\ne1\) nên \(2+x=4\Rightarrow x=2\)

Vậy.....

Câu e làm tương tự! Chúc bạn học tốt!!!

1) \(2^x-15=17\)

\(2^x=17+15=32=2^5\)

\(\Rightarrow x=5\)

2) \(\left(7x-11\right)^3=2^5.5^2+200=32.25+200=1000=10^3\)

\(\Rightarrow7x-11=10\)

\(7x=11+10=21\)

\(x=3\)

3) \(3^x+25=26.2^2+2.3^0=26.4+2=106\)

\(3^x=106-25=81=3^4\)

\(\Rightarrow x=4\)

4) \(49.7^x=2041\)

\(7^2.7^x=7^4\)

\(\Rightarrow2+x=4\)

x = 2.

5) \(3^x=243=3^5\)

\(\Rightarrow x=5\)

3^x+25=26.2⁰+2.3⁰
3^x+25=26.1+2.1
3^x+25=28
3^x=3
x=1

3x+25=26.20+2.30

3x+25=26.1+2.1

3x+25=28

3x=3

x=1

<=> 3^x+25= 26.4+2.1

<=> 3^x+25= 106

<=> 3^x= 106-25

<=> 3^x= 81

Mà 81= 3^4

=> x=4

\(3^x+25=26.2^2+2.3^0\)

\(3^x+25=104+2\)

\(3^x+25=106\)

\(3^x=81=3^4\)

          Vậy x=4

3^x+25=26 . 2^2 + 2. 3^0

3^x+25=104 +2

3^x+25=106

3^x=106+25

3^x=81=3^4

=> x=4                                                                      

3 

x

 +25=26.2 

2

 +2.3 

0

3

𝑥

+

25

=

104

+

2

3 

x

 +25=104+2

3

𝑥

+

25

=

106

3 

x

 +25=106

3

𝑥

=

81

=

3

4

3 

x

 =81=3 

4

          Vậy x=4

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

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

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

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

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

\(\Rightarrow7x-11=10.\)

\(\Rightarrow x=\left(10+11\right):3=7\in Z.\)

Vậy.....

\(b,3^x+25=26.2^2+2.3^0.\)

\(3^x+25=26.4+2.\)

\(3^x+25=104+2.\)

\(3^x+25=106.\)

\(3^x=106-25.\)

\(3^x=81.\)

\(3^x=3^4\Rightarrow x=4\in Z.\)

Vậy.....

\(c,2^x+3.2=64.\)(có vấn đề).

\(d,5^{x+1}+5^x=750.\)

\(5^x.5^1+5^x+1=750.\)

\(5^x\left(5^1+1\right)=750.\)

\(5^x\left(5+1\right)=750.\)

\(5^x.6=750.\)

\(5^x=750:6.\)

\(5^x=125.\)

\(5^x=5^3\Rightarrow x=3\in Z.\)

Vậy.....

\(e,x^{15}=x.\)

\(\Rightarrow x\left(x^{14}-1\right)=0\Rightarrow\left\{{}\begin{matrix}x=0\\x=1\end{matrix}\right..\)

\(f,\left(x-5\right)^4=\left(x-5\right)^6.\)

\(\Leftrightarrow\left(x-5\right)^4-\left(x-5^6\right)=0.\)

\(\Leftrightarrow\left(x-5\right)^4\left[1-\left(x-5\right)^2\right]=0.\)

\(\Leftrightarrow\left(x-5\right)^4\left(1-x+5\right)\left(1+x-5\right)=0.\)

\(\Leftrightarrow\left(x-5\right)^4\left(6-x\right)\left(x-4\right)=0.\)

\(\Leftrightarrow\left(x-5\right)^4=0\Rightarrow x-5=0\Rightarrow x=5\in Z.\)

\(6-x=0\Rightarrow x=6\in Z.\)

\(x-4=0\Rightarrow x=4\in Z.\)

Vậy.....