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a. Ta có : 2,5 < 5,2 => 2,53 < 5,23
b. Ta có : 45 = 1024 ; 54 = 625
Vì 1024 > 625 => 45 > 54
\(a.2.5^3va5.2^3\)
\(2.5^3=2.125=250;5.2^3=5.8=40\)
Vì \(250>40\)
\(\Rightarrow2.5^3>5.2^3\)
\(b.4^5va5^4\)
\(4^5=1024;5^4=625\)
Vì \(1024>625\)
\(\Rightarrow4^5>5^4\)
\(c.2^8va2.5^3\)
\(2^8=256;2.5^3=2.125=250\)
Vì \(256>250\)
\(\Rightarrow2^8>2.5^3\)
2.Tìm x:
\(a.2^n+4.2^n=5.2^5\)
\(2^n\left(1+4\right)=5.32\)
\(2^n.5=160\)
\(2^n=160:5\)
\(2^n=32\)
\(2^n=2^5\)
\(\Rightarrow n=5\)
\(b.3^4.3^n:9=3^7\)
\(3^4.3^n:3^2=3^7\)
\(3^4.3^n=3^7.3^2\)
\(3^4.3^n=3^{7+2}\)
\(3^4.3^n=3^9\)
\(3^n=3^9:3^4\)
\(3^n=3^{9-4}\)
\(3^n=3^5\)
\(\Rightarrow n=5\)
\(c.6.2^n+3.2^n=9.2^n\)
\(2^n\left(6+3\right)=9.2^n\)
\(2^n.9=9.2^n\)
\(\Rightarrow2^n=9:9\)
\(\Rightarrow2^n=1\)
\(\Rightarrow2^n=2^0\)
\(\Rightarrow n=0\)
Chúc bạn học tốt!
a)
\(3^4.3^n:9=3^7\)
\(\Rightarrow3^4.3^n=3^7.9\)
\(\Leftrightarrow3^4.3^n=3^7.3^2\)
\(\Rightarrow3^4.3^n=3^9\)
\(\Rightarrow3^n=3^9:3^4\)
\(\Rightarrow3^n=3^5\)
\(\Rightarrow n=5\)
Vậy \(n=5\)
d)
\(2^n:4=16\)
\(\Leftrightarrow2^n:2^2=2^4\)
\(\Rightarrow2^n=2^4.2^2\)
\(\Rightarrow2^n=2^6\)
\(\Rightarrow n=6\)
Vậy \(n=6\)
\(2^n:4=16\Rightarrow2^n=64\Rightarrow2^n=2^6\Rightarrow n=6\)
\(3^n:3^2=243\Rightarrow3^n=2187\Rightarrow3^n=3^7\Rightarrow n=7\)
\(a,2.16\le2^n< 4\)
\(\Rightarrow2^5\le2^n< 2^2\)
\(\Rightarrow n\in5,4,3\)
\(b,3^2.3^n=3^5\)
\(\Rightarrow3^n=3^5:3^2\)
\(\Rightarrow3^n=3^2\)
\(\Rightarrow n=2\)
\(c,\left(2^2:4\right):2^n=4\)
\(\Rightarrow1:2^n=4\)
\(\Rightarrow2^n=1:4=\frac{1}{4}\)
mà \(n\in N\)nên n ko có giá trị nào
\(d,\frac{1}{9}.3^4.3^n=3^7\)
\(\Rightarrow\left(\frac{1}{3}\right)^2.3^2.3^2.3^n=3^7\)
\(\Rightarrow3^2.3^n=3^7\)
\(\Rightarrow3^n=3^7:3^2\)
\(\Rightarrow3^n=3^5\)
\(\Rightarrow n=5\)
e,f làm tự làm tiếp nhé,mỏi tay wa
Trả lời
a)58:52=56
b)37:34=33
c)274:95=(33)4:(32)5=312:310=32
Bài 2:
a)n=4
b)n=3
c)n=2
d)n=4
\(a,3^n=3^4\)
\(\Rightarrow n=4\)
\(b,2008^n=2008^0\)
\(\Rightarrow n=0\)
\(2^n+4.2^n=255.2^5\)
\(2^n.\left(1+4\right)=255.2^5\)
\(2^n.5=8160\)
\(2^n=1632\)
mà \(n\)thuộc N => nthuoojc rỗng
\(2^n-64=2^6\)
\(2^n=128\)
\(2^n=2^7\)
\(n=7\)
\(3^4.3^n:9=3^7\)
\(3^4.3^n:3^2=3^7\)
\(3^{4+n}=19683\)
\(3^{4+n}=3^9\)
\(4+n=9\)
\(n=5\)
\(3^4.3^n:9=3^7\)
\(3^{4+n-2}=3^7\)
\(3^{2+n}=3^7\)
\(\Rightarrow2+n=7\)
\(\Rightarrow x=5\)
Vậy \(n=5\)