Question

tìm x biết 

a, 3 mũ x = 9 

b, 6 mũ x - 1 = 36 

c, 5 mũ x = 125 

3 mũ 2x =+ 1 = 27

3 mũ x + 1 = 9

x mũ 50 = x

Answer 1

a)\(3^x=9\Leftrightarrow x^x=3^2\Leftrightarrow x=2\)

b)\(6^{x-1}=36\Leftrightarrow6^{x-1}=6^2\Leftrightarrow x-1=2\Leftrightarrow x=3\)

c)\(5^x=125\Leftrightarrow5^x=5^3\Leftrightarrow x=3\)

d)\(3^{2x+1}=27\Leftrightarrow3^{2x+1}=3^3\Leftrightarrow2x+1=3\Leftrightarrow2x=2\Leftrightarrow x=1\)

e) \(3^{x+1}=9\Leftrightarrow3^{x+1}=3^2\Leftrightarrow x+1=2\Leftrightarrow x=1\)

f) \(x^{50}=x\Leftrightarrow\hept{\begin{cases}x=1\\x=0\end{cases}}\)

Answer 2

\(3^x=9\)

\(\Rightarrow3^x=3^2\)

\(\Rightarrow x=2\)

Answer 3

a, 3^x = 9 => 3^x = 3² => x = 2

b, 6^{x - 1} = 36 => 6^{x - 1} = 6² => x - 1 = 2 => x = 3

c, 5^x = 125 => 5^x = 5³ => x = 3

d, 3^{2x + 1} = 27 => 3^{2x + 1} = 3³ => 2x + 1 = 3 => 2x = 2 => x = 1

e, 3^{x + 1} = 9 => 3^{x + 1} = 3² => x + 1 = 2 => x = 1

f, x⁵⁰ = x => x⁵⁰ - x = 0 => x . (x⁴⁹ - 1) = 0 => \(\orbr{\begin{cases}x=0\\x^{49}-1=0\end{cases}}\)=>\(\orbr{\begin{cases}x=0\\x=1\end{cases}}\)

Answer 4

a, \(3^x=9\Leftrightarrow3^x=3^2\Leftrightarrow x=2\)

b, \(6^{x-1}=36\Leftrightarrow6^{x-1}=6^2\Leftrightarrow x=3\)

c, \(5^x=125\Leftrightarrow5^x=5^3\Leftrightarrow x=3\)

d, \(3^{x+1}=9\Leftrightarrow3^{x+1}=3^2\Leftrightarrow x=1\)

e, \(x^{50}=x\Leftrightarrow x^{50}-x=0\Leftrightarrow x\left(x^{49}-1\right)=0\Leftrightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)