Question

Tìm số tự nhiên n biết:

a)3ⁿ=27

b)5ⁿ=625

c)12ⁿ=144

d)2ⁿx16=128

e)3ⁿ:9=27

f)(n-2)²=(n-2)⁴

g)n⁵=n²⁰¹⁸

Answer 1

a) \(27=3^3\Rightarrow3^n=3^3\Leftrightarrow n=3\)

b) \(625=5^4\Rightarrow5^n=5^4\Leftrightarrow n=4\)

c) \(144=12^2\Rightarrow12^n=12^2\Leftrightarrow n=2\)

d) \(128=8.16=2^3.16\Leftrightarrow2^n.16=2^3.16\Leftrightarrow n=3\)

Answer 2

\(a)3^n=27\Rightarrow n=3\)

\(b)5^n=625\Rightarrow n=4\)

\(c)12^n=144\Rightarrow n=2\)

\(d)2^n.16=128\Rightarrow n=3\)

\(f)\left(n-2\right)^2=\left(n-2\right)^4\Rightarrow n=1\)

\(g)n^5=n^{2018}\Rightarrow n=1\)