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a)\(3,8:\left(2x\right)=\dfrac{1}{4}:2\dfrac{2}{3}\)
\(2x=3,8:\dfrac{3}{32}\)
\(x=\dfrac{608}{15}:2\)
\(x=\dfrac{304}{15}\)
b)\(\left(0,25x\right):3=\dfrac{5}{6}:0,125\)
\(0,25x=\dfrac{20}{3}\times3\)
\(x=20:0,25\)
\(x=80\)
c) \(0,01:2,5=\left(0,75\times x\right):0,75\)
\(0,004=0,75\times x:0,75\)
\(0,004=x\times0,75:0,75\)
\(0,004=x\times1\)
\(0,004=x\)
\(\Rightarrow x=0,004\)
d)\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:\left(0,1x\right)\)
\(\dfrac{5}{3}=\dfrac{2}{3}:0,1\times x\)
\(\dfrac{5}{3}=\dfrac{20}{3}\times x\)
\(\Rightarrow x=\dfrac{20}{3}:\dfrac{5}{3}\)
\(x=4\)
a) \(x=20\dfrac{4}{15}.\)
b) \(x=80\)
c) \(x=0,004\)
d) \(x=4.\)
a: TH1: x>=0
=>x+x=1/3
=>x=1/6(nhận)
TH2: x<0
Pt sẽ là -x+x=1/3
=>0=1/3(loại)
b: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\x^2-x-2=0\end{matrix}\right.\Leftrightarrow x=2\)
c: \(\Leftrightarrow\dfrac{1}{x-1}-\dfrac{1}{x-3}+\dfrac{1}{x-3}-\dfrac{1}{x-8}+\dfrac{1}{x-8}-\dfrac{1}{x-20}-\dfrac{1}{x-20}=\dfrac{-3}{4}\)
\(\Leftrightarrow\dfrac{1}{x-1}-\dfrac{2}{x-20}=\dfrac{-3}{4}\)
\(\Leftrightarrow\dfrac{x-20-2x+2}{\left(x-1\right)\left(x-20\right)}=\dfrac{-3}{4}\)
\(\Leftrightarrow-3\left(x^2-21x+20\right)=4\left(-x-18\right)\)
\(\Leftrightarrow3x^2-63x+60=4x+72\)
=>3x^2-67x-12=0
hay \(x\in\left\{22.51;-0.18\right\}\)
a) x = \(\dfrac{-64}{3}\)
b) x = -3,5
c) x = 80
d) x = -1.162
e) x = 0,9436
g) x \(\in\varnothing\)
a) 16/3 : x = -1/4
=> x = 16/3 : (-1/4)
=> x = 16/3 . (-4)
=> x = -64/3
Vậy x= -64/3
b)2x - 13 = -8
=> 2x = (-8) + 1
=> 2x = -7
=> x = -7/2
d) 0,944 - 2x = 3,268
=> 2x = 0,944 - 3,268
=> 2x = -2,324
=> x = (-2,324) : 2
=> x = -1,162
g) \(\sqrt{5^2-3^2}=-\sqrt{81-x}\)
=> \(\sqrt{25-9}\)= \(-\sqrt{81-x}\)
=> \(\sqrt{16}\)=\(-\sqrt{81-x}\)
=> 4=\(-\sqrt{81-x}\)
tới đây mik bí r hk bt lm nữa
1. Tìm x:
a) \(\left(x+36\right)^2=1936\Leftrightarrow x+36=\pm44.\) Vậy x = 8 hoặc x = -80
b) \(\left(\dfrac{3}{5}\right)^{x+2}=\dfrac{81}{625}\Leftrightarrow\left(\dfrac{3}{5}\right)^{x+2}=\left(\dfrac{3}{5}\right)^4\Leftrightarrow x+2=4\Leftrightarrow x=2\)
c) Xem lại đề
d) \(\left(\dfrac{9}{16}\right)^{x-5}=\left(\dfrac{4}{3}\right)^4\Leftrightarrow\left(\dfrac{3}{4}\right)^{2\left(x-5\right)}=\left(\dfrac{3}{4}\right)^{-4}\Leftrightarrow2\left(x-5\right)=-4\Leftrightarrow x=3\)
e) \(\left(\dfrac{3}{5}\right)^x.\left(\dfrac{125}{27}\right)^x=\dfrac{81}{625}\Leftrightarrow\left(\dfrac{3}{5}.\dfrac{125}{27}\right)^x=\left(\dfrac{3}{5}\right)^4\Leftrightarrow\left(\dfrac{5}{3}\right)^{2x}=\left(\dfrac{5}{3}\right)^{-4}\Leftrightarrow2x=-4\) Vậy x = -2
3. Tính giá trị của biểu thức:
\(A=\left\{-\left[\left(\dfrac{1}{x}\right)^2\right]^3\right\}^5.\left\{-\left[\left(-x\right)^5\right]^2\right\}^3\) \(\left(x\notin0\right)\)
\(=\left\{-\left[-\dfrac{1}{x^2}\right]^3\right\}^5.\left\{-\left[-\left(-x\right)^5\right]^2\right\}^3=\left\{-\left[-\dfrac{1}{x^6}\right]\right\}^5.\left\{-\left[x^5\right]^2\right\}^3\)
\(=\left\{\dfrac{1}{x^6}\right\}^5.\left\{-x^{10}\right\}^3=\dfrac{1}{x^{30}}.\left(-x^{30}\right)=-1\)
a: 10:15=14:21
=>10/14=15/21; 15/10=21/14; 14/10=21/15
b: 2/3:1/4=2/3x4=8/3
16/9:16/24=16/9x24/16=8/3
Do đó: \(\dfrac{\dfrac{2}{3}}{\dfrac{1}{4}}=\dfrac{\dfrac{16}{9}}{\dfrac{16}{24}}\)
Suy ra: \(\dfrac{\dfrac{2}{3}}{\dfrac{16}{9}}=\dfrac{\dfrac{1}{4}}{\dfrac{16}{24}};\dfrac{\dfrac{1}{4}}{\dfrac{2}{3}}=\dfrac{\dfrac{16}{24}}{\dfrac{16}{9}};\dfrac{\dfrac{16}{9}}{\dfrac{2}{3}}=\dfrac{\dfrac{16}{24}}{\dfrac{1}{4}}\)
a) x : ( -2,14) = (-3,12) :1,2
x : ( -2,14) = -2,6
x = -2,6 x ( -2,14)
x = 5,564
Vậy x = 5,564
b)\(2\dfrac{2}{3}\) : x = \(2\dfrac{1}{12}\) : ( -0,06)
\(2\dfrac{2}{3}\) : x = \(-\dfrac{625}{18}\)
x = \(2\dfrac{2}{3}\) : \(-\dfrac{625}{18}\)
x =
x = -0,0768
Vậy x = -0,0768
( Mình bấm nhầm, bổ sung nha)