Question

[Mai Chi Nguyễn]

2//Tìm n ∈ N biết

a)\(2008^n=1\)

b)\(32^{-n}.16^n=1024\)

c)\(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}.\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=2^n\)

3/Tìm các số tự nhiên x,y biết

a)\(2^{x+1}.3^y=12^x\)

b)\(10^x:5^y=20^y\)

các bạn giúp mình với!!!!!!HELP ME !!!!!

Answer 1

[Hà Đức Anh]

Bài 2 : Bài giải

a, \(2008^n=1=2008^0\)

\(\Rightarrow\text{ }n=0\)

b, \(32^{-n}\cdot16^n=1024\)

\(\left(2^5\right)^{-n}\cdot\left(2^4\right)^n=2^{10}\)

\(2^{-5n}\cdot2^{4n}=2^{10}\)

\(2^{-n}=2^{10}\)

\(\Rightarrow\text{ }n=-10\)

c, \(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}\cdot\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=2^n=\frac{4\cdot4^5}{3\cdot3^5}\cdot\frac{6\cdot6^5}{2\cdot2^5}=\frac{4^6}{3^6}\cdot\frac{6^6}{2^6}=2^6\cdot2^6=2^{12}\)

\(\Rightarrow\text{ }n=12\)