Question

Tìm x:a,
\(5^x+5^{x+2}=650\)

b,\(4^x+4^{x+3}=4160\)

Answer 1

a. Ta có : \(^{ }\)

Answer 2

a/ \(5^x+5^{x+2}=650\)

\(\Leftrightarrow5^x\left(1+5^2\right)=650\)

\(\Leftrightarrow5^x.26=650\)

\(\Leftrightarrow5^x=25\)

\(\Leftrightarrow5^x=5^2\)

\(\Leftrightarrow x=2\)

Vậy ...

b/ \(4^x+4^{x+3}=4160\)

\(\Leftrightarrow4^x\left(1+4^3\right)=4160\)

\(\Leftrightarrow4^x.65=4160\)

\(\Leftrightarrow4^x=64\)

\(\Leftrightarrow4^x=4^3\)

\(\Leftrightarrow x=3\)

Vậy ...

Answer 3

a) 5^x + 5^x+2 =650

\(\Rightarrow5^x\left(1+5^2\right)=650\)

\(\Rightarrow5^x\left(1+25\right)=650\Rightarrow5^x.26=650\Rightarrow5^x=25\Rightarrow x=2\)

b) \(4^x+4^{x+3}=4160\)

\(\Rightarrow4^x\left(1+4^3\right)=4160\Rightarrow4^x.65=4160\Rightarrow4^x=64\Rightarrow x=3\)