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a) \(\Rightarrow3^n=3^5:3^2=3^3\)
\(\Rightarrow n=3\)
b) \(1\times2^n=4\)
\(\Rightarrow2^n=4:1=4=2^2\)
\(\Rightarrow n=2\)
c) \(3^2\times3^n=3^7\)
\(\Rightarrow3^n=3^7:3^2=3^5\)
\(\Rightarrow n=5\)
d) \(\frac{1}{9}=\left(\frac{1}{3}\right)^2\)
\(\left(\frac{1}{3}\right)^2\times27^n=3^n\)
Làm tới đây rồi khúc sau thực sự không chắc lắm
\(a,2.16\le2^n< 4\)
\(\Rightarrow2^5\le2^n< 2^2\)
\(\Rightarrow n\in5,4,3\)
\(b,3^2.3^n=3^5\)
\(\Rightarrow3^n=3^5:3^2\)
\(\Rightarrow3^n=3^2\)
\(\Rightarrow n=2\)
\(c,\left(2^2:4\right):2^n=4\)
\(\Rightarrow1:2^n=4\)
\(\Rightarrow2^n=1:4=\frac{1}{4}\)
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
Trl :
\(\frac{1}{9}.27^n=3^{n+2}\)
\(3^{-2}.\left(3^3\right)^n=3^{n+2}\)
\(3^{-2}.3^{3n}=3^{n+2}\)
\(\Rightarrow-2+3n=n+2\)
\(\Rightarrow3n=n+4\)
\(\Rightarrow2n=4\)\(\Rightarrow n=2\)
Hok tốt
Trl :
\(\frac{1}{9}3^4.3^n=3^7\)
\(3^{-2}.3^4.3^n=3^7\)
\(\Rightarrow-2+4+n=7\)
\(\Rightarrow2+n=7\)
\(\Rightarrow n=7-2\)
\(\Rightarrow n=5\)
Hok tốt !
1.
a) ( 57 + 59 ) . ( 68 + 610 ) . ( 24 - 42 )
= ( 57 + 59 ) . ( 68 + 610 ) . 0
= 0
b) 9 < 3x < 27
32 < 3x < 33
2 < x < 3
Vậy 2 < x < 3
2.
a) xy - 2x = 0
x ( y - 2 ) = 0
\(\Rightarrow\orbr{\begin{cases}x=0\\y-2=0\end{cases}\Rightarrow\orbr{\begin{cases}x=3\\y=2\end{cases}}}\)
b) ( x- 4 ) . ( x - 3 ) = 0
\(\Rightarrow\orbr{\begin{cases}x-4=0\\x-3=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=4\\x=3\end{cases}}\)
c) Ta có : 3n+2 + 3n = 3n . 32 + 3n = 3n . ( 32 + 1 ) = 3n . 10 \(⋮\)10
\(a,3^n=3^4\)
\(\Rightarrow n=4\)
\(b,2008^n=2008^0\)
\(\Rightarrow n=0\)
a) \(n^{51}=n\)
\(\Rightarrow n^{51}-n=0\)
\(n\left(n^{50}-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}n=0\\n^{50}-1=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}n=0\\n^{50}=1\end{cases}}\)
\(\Rightarrow n\in\left\{-1;0;1\right\}\)
b) \(\frac{1}{9}.27^n=3^n\)
\(\Rightarrow3^{-2}.3^{3n}=3^n\)
\(3^{3n-2}=3^n\)
\(\Rightarrow3n-2=n\)
\(3n-n=2\)
\(2n=2\)
\(n=2:2=1\)
c) \(3^{-2}.3^4.3^n=3^7\)
\(3^{n+4-2}=3^7\)
\(3^{n+2}=3^7\)
\(\Rightarrow n+2=7\)
\(\Rightarrow n-7=5\)
d) \(32^{-n}.16^n=2048\)
\(2^{-5n}.2^{4n}=2^{10}\)
\(2^{4n-5n}=2^{10}\)
\(2^{-n}=2^{10}\)
\(\Rightarrow-n=10\)
\(\Rightarrow n=-10\)
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/\(\frac{1}{9}.3^4.3^n=3^7\)
\(\frac{1}{9}.81.3^n=3^7\)
\(\frac{81}{9}.3^n=3^7\)
\(9.3^n=3^7\)
\(3^2.3^n=3^7\)
\(3^2.3^n=3^2.3^5\)
vậy \(n=5\)
b/ \(\frac{1}{2}.2^n+4.2^n=9.2^5\)
\(2^n\left(\frac{1}{2}+4\right)=9.2^5\)
\(2^n.\frac{9}{2}=9.32\)
\(2^n.\frac{9}{2}=288\)
\(2^n=288:\frac{9}{2}\)
\(2^n=64\)
\(2^n=2^6\)
Vậy \(n=6\)
hhhhhhhhhhhh