`a,(n-3)^5=(n-3)^2`
`⇔` \(\left[ \begin{array}{l}n-3=0\\n-3=1\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}n=0 + 3\\⇒ n = 3\\n=1 + 3\\⇒n = 4\end{array} \right.\)
`b, 5^n+5^{n+1} =750`
`⇔ 5^n(1+5)=750`
`⇔ 5^n = 125`
`⇔ 5^n = 5^3`
`⇒ n = 3`
Học tốt !