Question

tìm x biết 

a. (2x+1)^2=25

b.  5^2x+1=125

Answer 1

a. 

(2x+1)² = 25 = 5²

=> 2x + 1 = 5

=> 2x = 4

=> x = 2

Vậy x = 2

b.

5^2x+1 = 125 = 5³

=> 2x + 1 = 3

=> 2x = 2

=> x = 1 

Vậy x = 1

Chúc em học tốt!!!

Answer 2

a, ( 2x + 1 )² = 25

<=> ( 2x + 1 )² = 5²

=> 2x + 1 = 5

=> 2x = 4

=> x = 2

b 5^{2x + 1} = 125

<=> 5^2x+1  = 5³

=> 2x + 1 = 3

=> 2x = 2

=> x = 1

Answer 3

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

\(\left(2x+1\right)^2=\left(\pm5\right)^2\)

\(\Rightarrow\orbr{\begin{cases}2x+1=5\\2x+1=-5\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=-3\end{cases}}\)

\(5^{2x+1}=125\)

\(\Rightarrow5^{2x+1}=5^3\)

\(\Rightarrow2x+1=3\)

\(\Rightarrow x=2\)

Answer 4

a. \(\left(2x+1\right)^2=25\)

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

\(\Leftrightarrow2x+1=5\)

\(\Leftrightarrow2x=6\)

\(\Rightarrow x=3\)

b. \(5^{2x+1}=125\)

\(\Leftrightarrow5^{2x+1}=5^5\)

\(\Leftrightarrow2x+1=3\)

\(\Leftrightarrow2x=4\)

\(\Rightarrow x=2\)

Answer 5

a, ( 2x + 1 )² = 25

<=> (2x + 1 )² = 5²

=> 2x + 1 = 5

=> 2x = 4

=> x = 4 : 2

=> x = 2

Answer 6

b, 5^{2x +1} = 125

<=> 5^{2x + 1} = 5³

=> 2x + 1 = 3

=> 2x = 2

=> x = 1