Question

Tìm x, biết:

a) 2^x = 16

b) 3^x+1 = 9^x

c) 2^3x+2 = 4^x+5

d) 3^2x-1 = 243

Answer 1

a

\(\Rightarrow\)\(2^x=16\)

\(\Rightarrow\) \(2^4\)

Answer 2

b) \(3^{x+1}=9^x=3^{2x}\)

\(\Rightarrow x+1=2x\Leftrightarrow x=1\)

c) \(2^{3x+2}=4^x+5\Leftrightarrow4^{2x+1}=4^{x+5}\)

\(\Rightarrow2x+1=x+5\)\(\Rightarrow x=4\)

d) \(3^{2x-1}=243=3^5\)

\(\Rightarrow2x-1=5\Rightarrow x=3\)

Answer 3

a) \(2^x=16\)

\(\Rightarrow2^x=2^4\)

\(\Rightarrow x=4\)

Vậy \(x=4.\)

b) \(3^{x+1}=9^x\)

d) \(3^{2x-1}=243\)

\(\Rightarrow3^{2x-1}=3^5\)

\(\Rightarrow2x-1=5\)

\(\Rightarrow2x=5+1\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=6:2\)

\(\Rightarrow x=3\)

Vậy \(x=3.\)

Chúc bạn học tốt!