Question

Tìm x:

a) \(\left(5x-1\right)^6=729\) b) \(\dfrac{8}{25}=\dfrac{2^x}{5^{x-1}}\) c) \(\left(\dfrac{1}{16}\right)^x=\left(\dfrac{1}{2}\right)^{10}\) d) \(9^x:3^x=3\)

Answer 1

a) \(\left(5x-1\right)^6=729\)

\(\Leftrightarrow5x-1=3\)

\(\Leftrightarrow5x=4\)

\(\Leftrightarrow x=\dfrac{4}{5}\)

Answer 2

b: \(\Leftrightarrow\dfrac{2^3}{5^2}=\dfrac{2^x}{5^{x-1}}\)

=>x=3 và x-1=2

=>x=3

c: \(\Leftrightarrow\left(\dfrac{1}{2}\right)^{4x}=\left(\dfrac{1}{2}\right)^{10}\)

=>4x=10

=>x=5/2

d: =>3^x=3

=>x=1