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a) Câu này thiếu đề nhé bạn.
b) \(\frac{25}{5^n}=5\)
\(\Rightarrow5^n=25:5\)
\(\Rightarrow5^n=5\)
\(\Rightarrow5^n=5^1\)
\(\Rightarrow n=1\)
Vậy \(n=1.\)
c) \(\frac{81}{\left(-3\right)^n}=-243\)
\(\Rightarrow\left(-3\right)^n=81:\left(-243\right)\)
\(\Rightarrow\left(-3\right)^n=-\frac{1}{3}\)
\(\Rightarrow\left(-3\right)^n=\left(-3\right)^{-1}\)
\(\Rightarrow n=-1\)
Vậy \(n=-1.\)
e) \(\left(\frac{1}{3}\right)^n=\frac{1}{81}\)
\(\Rightarrow\left(\frac{1}{3}\right)^n=\left(\frac{1}{3}\right)^4\)
\(\Rightarrow n=4\)
Vậy \(n=4.\)
f) \(\left(-\frac{3}{4}\right)^n=\frac{81}{256}\)
\(\Rightarrow\left(-\frac{3}{4}\right)^n=\left(-\frac{3}{4}\right)^4\)
\(\Rightarrow n=4\)
Vậy \(n=4.\)
Chúc bạn học tốt!
d) \(\frac{1}{2}.2^n+4.2^n=9.2^5\)
\(\Rightarrow2^n.\left(\frac{1}{2}+4\right)=288\)
\(\Rightarrow2^n.\frac{9}{2}=288\)
\(\Rightarrow2^n=288:\frac{9}{2}\)
\(\Rightarrow2^n=64\)
\(\Rightarrow2^n=2^6\)
\(\Rightarrow n=6\)
Vậy \(n=6.\)
g) \(-\frac{512}{343}=\left(-\frac{8}{7}\right)^n\)
\(\Rightarrow\left(-\frac{8}{7}\right)^n=\left(-\frac{8}{7}\right)^3\)
\(\Rightarrow n=3\)
Vậy \(n=3.\)
h) \(5^{-1}.25^n=125\)
\(\Rightarrow5^{-1}.5^{2n}=5^3\)
\(\Rightarrow5^{-1+2n}=5^3\)
\(\Rightarrow-1+2n=3\)
\(\Rightarrow2n=3+1\)
\(\Rightarrow2n=4\)
\(\Rightarrow n=4:2\)
\(\Rightarrow n=2\)
Vậy \(n=2.\)
k) \(3^{-1}.3^n+6.3^{n-1}=7.3^6\)
\(\Rightarrow3^{n-1}+6.3^{n-1}=7.3^6\)
\(\Rightarrow3^{n-1}.\left(1+6\right)=7.3^6\)
\(\Rightarrow3^{n-1}.7=7.3^6\)
\(\Rightarrow n-1=6\)
\(\Rightarrow n=6+1\)
\(\Rightarrow n=7\)
Vậy \(n=7.\)
Chúc bạn học tốt!
a: \(=3^2\cdot3^5:3^4=3^{2+5-4}=3^3\)
b: \(=2^3\cdot2^4:\left(\dfrac{8}{16}\right)=\dfrac{2^7}{2}=2^6\)
c: \(=3^7\cdot3^3=3^{10}\)
d: \(=5^3\cdot5^2\cdot\dfrac{1}{5^4}=5^1\)
Bạn 12345678901 xuống lớp 1 học đạo đức làm người nhé bạn. Lịch sự tí đi
\(\frac{16}{2^n}=1;2^n=8;n=3\)
\(\frac{\left(-3\right)^n}{81}=-27;\left(-3\right)^n=\left(-3\right)^7;n=7\)
\(8^n:2^n=4;\left(8:2\right)^n=4;4^n=4=4^1;n=1\)
a, \(\frac{16}{2^n}=2\Leftrightarrow16=2^n.2\Rightarrow2^4=2^{n+1}\Rightarrow n+1=4\Rightarrow n=3\)
b) \(\frac{\left(-3\right)^n}{81}=-27\Rightarrow\left(-3\right)^n=-27.81\Rightarrow\left(-3\right)^n=-3^3.3^4\Rightarrow\left(-3\right)^n=\left(-3\right)^7\Rightarrow n=7\)
c, \(8^n:2^n=4\Leftrightarrow2^{3n}:2^n=2^2\Leftrightarrow2^{2n}=2^2\Leftrightarrow2n=2\Rightarrow n=1\)
a: \(=3^2\cdot3^3\cdot3^{-4}\cdot3^2=3^{2+3-4+2}=3^3\)
b: \(=2^2\cdot2^5:\left(2^3\cdot\dfrac{1}{2^4}\right)=2^7:\dfrac{1}{2}=2^8\)
c: \(=9\cdot32\cdot\dfrac{4}{9}=128=2^7\)
d: \(=\dfrac{1}{27}\cdot3^4=3^1\)
a) \(\frac{\left(-3\right)^n}{81}=-27\)
\(\Rightarrow\left(-3\right)^n=-2187\)
\(\Rightarrow\left(-3\right)^n=\left(-3\right)^7\)
\(\Rightarrow n=7\)
Vậy \(n=7\)
b) \(8^n:2^n=4\)
\(8^n:2^n=4^1\)
mà \(8:2=4\)
\(\Rightarrow n=1\)
Vậy \(n=1\)
Qùa tặng cuộc sống(1 bài)
a) 16 = 2,2n
24 = 2n+1
4 = n+1 => n = 3
Vcl giờ mới trả lời thì ông làm đc hết rồi