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a)72x+72x.49=2450
72x.50=2450
72x=2450:50=49
72x=72
2x=2
x=1
b)(33:11)x=81
3x=81
3x=34
x=4
c)1/6=2/3:8x
8x=2/3:1/6
8x=4
x=1/2
d)(x+1)3=64
(x+1)3=43
x+1=4
x=3
minh chỉ lam đc vậy thôi nha !hi hi
a) \(\frac{16}{2^3}\)=2
b) \(\frac{\left(-3\right)^7}{81}\)=-27
c)81 : 21 =4
Qùa tặng cuộc sống(1 bài)
a) 16 = 2,2n
24 = 2n+1
4 = n+1 => n = 3
\(a,\frac{16}{2^n}=2\Rightarrow2^n=16:2\Rightarrow2^n=8\Rightarrow2^n=2^3\Rightarrow n=3\)
\(b,\frac{\left(-3\right)^n}{81}=-27\Rightarrow\left(-3\right)^n=81.\left(-27\right)\Rightarrow\left(-3\right)^n=-2187\Rightarrow3^n=3^7\Rightarrow n=7\)
\(c,8^n:2^n=4\Rightarrow4^n=4\Rightarrow n=1\)
\(a,\frac{16}{2^n}=2\) \(b,\frac{\left(-3\right)^n}{81}=-27\) \(c,8^n:2^n=4\)
\(\Rightarrow2^4=2^n.2\) \(\Rightarrow\left(-3\right)^n=\left(-27\right).81\) \(\Rightarrow\left(8:2\right)^n=4\)
\(\Rightarrow4=n+1\) \(\Rightarrow\left(-3\right)^n=\left(-3\right)^7\) \(\Rightarrow4^n=4\)
\(\Rightarrow n=4-1=3\) \(\Rightarrow n=7\) \(\Rightarrow n=1\)
1.a.\(\left(1+\frac{2}{3}-\frac{1}{4}\right).\left(\frac{4}{5}-\frac{3}{4}\right)^2=\frac{17}{12}.\left(\frac{1}{20}\right)^2=\frac{17}{12}.\frac{1}{400}=\frac{17}{4800}\)
b. \(2\div\left(\frac{1}{2}-\frac{2}{3}\right)^3=2\div\left(-\frac{1}{6}\right)^3=2\div\left(-\frac{1}{216}\right)=2.\left(-216\right)=-432\)
2.a.\(\frac{16}{2^n}=2\Rightarrow2^n=16:2=8=2^3\Rightarrow n=3\)
b.\(\frac{\left(-3\right)^n}{81}=-27\Rightarrow\left(-3\right)^n=-27.81=-2187=\left(-3\right)^7\Rightarrow n=7\)
c. \(8^n:2^n=4\Rightarrow\left(8:2\right)^n=4\Rightarrow4^n=4^1\Rightarrow n=1\)
a)\(\frac{27}{3^{n+1}}=3^2\Leftrightarrow\frac{27}{3^{n+1}}=9\)
\(\Leftrightarrow3^{n+1}=27\div9\)
\(\Leftrightarrow3^{n+1}=3\)
\(\Leftrightarrow3^{n+1}=3^1\)
\(\Leftrightarrow n+1=1\)
\(\Rightarrow n=1-1\)
\(\Rightarrow n=0\)
=> Tích
Tìm số tự nhiên n, biết:
a) \(\frac{16}{2^n}=2\)
b) \(\frac{\left(-3\right)^n}{81}=-27\)
c) \(8^n:2^2\)
a) \(\frac{16}{2^n}=2\)
=> 16 = 2 . 2n
=> 16 = 2n+1
=> 24 = 2n+1
=> n + 1 = 4
=> n = 4 - 1
=> n = 3
Vậy n = 3
b) \(\frac{\left(-3\right)^n}{81}=-27\)
=> (-3)n = -27 . 81
=> (-3)n = (-3)3 . (-3)4
=> (-3)n = (-3)7
=> n = 7
Vậy n = 7
c) 8n : 22 = bao nhiêu vậy ban?
Chuk bn hk tốt!
a)\(\frac{16}{2^n}=2\)
\(\Rightarrow16:2=2^n\)
2n=8=23
Vậy n=3
b)\(\frac{\left(-3\right)^n}{81}=-27\)
\(\Rightarrow\)(-3)n=-27.81
(-3)n=-2187=(-3)7
Vậy n=7
c)Mk ko hiểu bn ghi gì
