Tìm x biết:
a, \(81^{-2x}.27^x=9^5\)
b, \(2^x+2^{x+3}=144\)
c, \(2^{x-1}+5.2^{x-2}=7.32\)
a) \(81^{-2x}.27^x=9^5\)
\(\Rightarrow\left(3^4\right)^{-2x}.\left(3^3\right)^x=3^{10}\)
\(\Rightarrow3^{-8x}.3^{3x}=3^{10}\)
\(\Rightarrow3^{-5}=3^{10}\)
\(\Rightarrow-5x=10\)
\(\Rightarrow x=-2\)
Vậy \(x=-2\)
b) \(2^x+2^{x+3}=144\)
\(\Rightarrow\left(1+2^3\right).2^x=144\)
\(\Rightarrow\left(1+8\right).2^x=144\)
\(\Rightarrow9.2^x=144\)
\(\Rightarrow2^x=16\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
c) \(2^{x-1}+5.2^{x-2}=7.32\)
\(\Rightarrow\left(2+5\right).2^{x-2}=244\)
\(\Rightarrow7.2^{x-2}=244\)
\(\Rightarrow2^{x-2}=32\)
\(\Rightarrow x-2=5\)
\(\Rightarrow x=7\)
Vậy \(x=7\)
Tính : 3^7.2^8 / 6^7
Bài 1:1)\(\left(\dfrac{-3}{2}\right)^x\)=\(\dfrac{9}{4}\)
2)\(3^{2x+2}=9^{10}\)
3)\(3^{3-2x}=27^{13}\)
4)\(5.3^x=7.3^5-2.3^5\)
Giúp mk với
Tính m , n ,p biết :
a) \(\left(\dfrac{1}{3}\right)^m=\dfrac{1}{81}\) b) \(\left(\dfrac{3}{5}\right)^n=\left(\dfrac{9}{25}\right)^5\)
c) \(\left(-0,25\right)^p=\dfrac{1}{256}\)
1. Tính:
C= \(\left(\dfrac{1}{2^2-1}\right)\left(\dfrac{1}{3^2-1}\right)\left(\dfrac{1}{4^2-1}\right)-.\left(\dfrac{1}{100^2-1}\right)\)
2. Tìm x:
\(\left(\dfrac{2}{5}\right)^x>\left(\dfrac{5}{2}\right)^{-3}.\left(\dfrac{-2}{5}\right)^2\)
Help me!!!
(X+1):25=4:(X+2)
(X+1)/25=4/(X+2)
Tìm x:
4/16 = 100/x2 -41
Bài1: tìm x biết
a) l x - 3,5 l = 7,5
b) l x + \(\dfrac{4}{5}\) l - \(\dfrac{1}{2}\) = 0
c) 3,6 - l x - 0,4 l = 0
d) \(\dfrac{-5}{12}\) : | \(\dfrac{-5}{6}\) : x | = \(\dfrac{-5}{9}\)
e) | x - 3,5|+|4,5- x|=0 bài 2:tính hợp lý
a) (-4,3)=[(-7,5)=(4,3)]
b) 45,3 + [(7,3)+(-22)]
c) [(-11.7)+5.5]+[11.7+(2.5)]
d) [(-6.8)+(-56.9)]+[2.8+5.9]
-4/13 x 5/17 + -12/13 x 4/17 + 4/13
thực hiện phép tính
mn giúp vs mk đag rất gấp
Tìm x, biết
a/ (x + 1 ) (x - 2 ) <0
b/ (x - 3 ) (x - 4 ) > 0
c/\(\dfrac{1}{2}\)-(\(\dfrac{1}{3}\)+\(\dfrac{1}{4}\))
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