Question

tìm x: 5^x-2+ 5^x+2=3130

Answer 1

\(5^{x-2}+5^{x+2}=3130\\ 5^{x-2}.\left(1+5^4\right)=3130\\ 5^{x-2}.626=3130\\ 5^{x-2}=\dfrac{3130}{626}=5\\ Vậy:5^{x-2}=5\\ Vậy:x-2=1\\ Vậy:x=3\)

Answer 2

\(5^{x-2}+5^{x+2}=3130\)

\(\Rightarrow5^x\cdot\left(5^{-2}+5^2\right)=3130\)

\(\Rightarrow5^x\cdot\left(\dfrac{1}{25}+25\right)\)

\(\Rightarrow5^x\cdot\dfrac{626}{25}=3130\)

\(\Rightarrow5^x=3130:\dfrac{626}{25}\)

\(\Rightarrow5^x=125\)

\(\Rightarrow5^x=5^3\)

\(\Rightarrow x=3\)

Vậy: x=3