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BT
8 tháng 7 2017
a/ \(\frac{2}{3}.3^{x+1}-7.3^x=405\)
<=> 2.3x-7.3x=-405
<=> 5.3x=405
<=> 3x=81 = 34
=> x=4
b/ (0,4x-1,3)2=5,29=(2,3)2
=> \(\hept{\begin{cases}0,4x-1,3=2,3\\0,4x-1,3=-2,3\end{cases}}\)=> \(\hept{\begin{cases}x=9\\x=-\frac{5}{2}\end{cases}}\)
c/ 5.2x+1.2-2-2x=384
<=> 5.2x-1-2.2x-1=384
<=> 3.2x-1=384
<=> 2x-1=128=27
=> x-1=7 => x=8
d/ 3x+2.5y=45x
<=> 3x+2.5y=32x.5x
=> \(\hept{\begin{cases}x+2=2x\\x=y\end{cases}}\)=> x=y=2
IS
4
27 tháng 7 2017
a) 4x + 4x + 3 = 4160
4x + 4x . 43 = 4160
4x .( 1 + 43 ) = 4160
4x . 65 = 4160
4x = 4160 : 65
4x = 64 => 4x = 43 => x = 3
b) 5x + 5x + 2 = 650
5x + 5x . 52 = 650
5x . ( 1 + 52 ) = 650
5x . 26 = 650 => 5x = 650 : 26 = 25 => 5x = 52 => x = 2
20 tháng 5 2022
a: \(\Leftrightarrow3^x\cdot\left(\dfrac{2}{3}\cdot3-7\right)=405\)
\(\Leftrightarrow3^x=-81\)(vô lý)
b: \(\left(0,4x-1,3\right)^2=5,29\)
=>0,4x-1,3=2,3 hoặc 0,4x-1,3=-2,3
=>0,4x=3,6 hoặc 0,4x=-1
=>x=9 hoặc x=-2,5
c: \(5\cdot2^{x+1}\cdot2^{-2}-2^x=284\)
\(\Leftrightarrow2^x\cdot5\cdot2\cdot2^{-2}-2^x=284\)
\(\Leftrightarrow2^x\cdot\left(\dfrac{5}{2}-1\right)=284\)
\(\Leftrightarrow2^x=\dfrac{568}{3}\)(vô lý)
d: \(\Leftrightarrow4^x\left(1+4^3\right)=4160\)
\(\Leftrightarrow4^x=64\)
hay x=3
24 tháng 7 2019
a) \(\frac{4}{3}x-1=\frac{x}{5}\)
=> \(\frac{4}{3}x-\frac{1}{5}x=1\)
=> \(\frac{17}{15}x=1\)
=> \(x=1:\frac{17}{15}=\frac{15}{17}\)
b) \(x+50\%=\frac{4\left(x+1\right)}{3}-\frac{1}{3}\)
=> \(x+\frac{1}{2}=\frac{4x+4-1}{3}\)
=> \(\frac{2x+1}{2}=\frac{4x+3}{3}\)
=> \(\left(2x+1\right).3=2.\left(4x+3\right)\)
=> \(6x+3=8x+6\)
=> \(6x-8x=6-3\)
=> \(-2x=3\)
=> \(x=3:\left(-2\right)=-\frac{3}{2}\)
24 tháng 7 2019
\(a,\frac{4}{3}x-1=\frac{x}{5}\)
\(\Rightarrow\frac{4}{3}x=\frac{x}{5}+1\)
\(\Rightarrow\frac{4x}{3}=\frac{x+5}{5}\)
\(\Rightarrow20x=3x+15\)
\(\Rightarrow17x=15\)
\(\Rightarrow x=\frac{15}{17}\)
\(b,x+50\%=\frac{4\left(x+1\right)}{3}-\frac{1}{3}\)
\(\Rightarrow x+\frac{1}{2}=\frac{4x+4-1}{3}\)
\(\Rightarrow\frac{2x+1}{2}=\frac{4x+3}{3}\)
\(\Rightarrow3\left(2x+1\right)=\left(4x+3\right).2\)
\(\Rightarrow6x+3=8x+6\)
\(\Rightarrow2x=-3\)
\(\Rightarrow x=-\frac{3}{2}\)
\(c,-200\%.x+\frac{4}{3}=\frac{7}{4}\left(x+1\right)\)
\(\Rightarrow-2x+\frac{4}{3}=\frac{7}{4}x+\frac{7}{4}\)
\(\Rightarrow\frac{-6x+4}{3}=\frac{7x+7}{4}\)
\(\Rightarrow4\left(-6x+4\right)=\left(7x+7\right)3\)
\(\Rightarrow-24x+16=21x+21\)
\(\Rightarrow45x=-5\)
\(\Rightarrow x=-\frac{1}{7}\)
19 tháng 10 2016
a) \(\left(4x-13\right)^4+4^3=145\)
\(\Rightarrow\left(4x-13\right)^4+64=145\)
\(\Rightarrow\left(4x-13\right)^4=81\)
\(\Rightarrow4x-13=\pm3\)
+) \(4x-13=3\)
\(\Rightarrow4x=16\)
\(\Rightarrow x=4\)
+) \(4x-13=-3\)
\(\Rightarrow4x=10\)
\(\Rightarrow x=\frac{5}{2}\)
Vậy \(x=4\) hoặc \(x=\frac{5}{2}\)
b) \(3^{x+2}-3^x=72\)
\(\Rightarrow3^x.3^2-3^x=72\)
\(\Rightarrow3^x.\left(3^2-1\right)=72\)
\(\Rightarrow3^x.8=72\)
\(\Rightarrow3^x=9\)
\(\Rightarrow3^x=3^2\)
\(\Rightarrow x=2\)
Vậy \(x=2\)
c) \(2^{x+2}-2^{x-1}=224\)
\(\Rightarrow2^{x-1+3}-2^{x-1}=224\)
\(\Rightarrow2^{x-1}.2^3-2^{x-1}=224\)
\(\Rightarrow2^{x-1}.\left(2^3-1\right)=224\)
\(\Rightarrow2^{x-1}.7=224\)
\(\Rightarrow2^{x-1}=32\)
\(\Rightarrow2^{x-1}=2^5\)
\(\Rightarrow x-1=5\)
\(\Rightarrow x=6\)
Vậy x = 6
16 tháng 5 2018
a) \(\left(4,5-2x\right)\cdot1\frac{4}{7}=\frac{11}{7}\)
\(\left(\frac{9}{2}-2x\right)\cdot\frac{11}{7}=\frac{11}{7}\)
\(\left(\frac{9}{2}-2x\right)=\frac{11}{7}\div\frac{11}{7}\)
\(\left(\frac{9}{2}-2x\right)=1\)
\(2x=\frac{9}{2}-1\)
\(x=\frac{7}{2}\div2\)
\(x=\frac{7}{4}\)
b) \(|\frac{3}{4}\cdot x-\frac{1}{2}|-1=\frac{1}{4}\)
\(|\frac{3}{4}\cdot x-\frac{1}{2}|=\frac{1}{4}+1\)
\(|\frac{3}{4}\cdot x|=\frac{5}{4}+\frac{1}{2}\)
\(x=\frac{7}{4}\div\frac{3}{4}\)
\(x=\frac{7}{3}\)
c) \(\frac{1}{4}-|3-x|=-\frac{3}{4}\)
\(|3-x|=\frac{1}{4}-\left(-\frac{3}{4}\right)\)
\(|3-x|=1\)
\(x=3-1\)
\(\Rightarrow x=2\)
d) \(4\cdot\left(x-\frac{6}{7}\right)-\frac{3}{5}=1,4\)
\(4\cdot\left(x-\frac{6}{7}\right)-\frac{3}{5}=\frac{7}{5}\)
\(4\cdot\left(x-\frac{6}{7}\right)=\frac{7}{5}+\frac{3}{5}\)
\(4\cdot\left(x-\frac{6}{7}\right)=2\)
\(\left(x-\frac{6}{7}\right)=2\div4\)
\(x=\frac{1}{2}+\frac{6}{7}\)
\(x=\frac{19}{14}\)
\(\)
=> 4x[1 + 43] = 4160
=> 4x . 65 = 4160
=> 4x = 64
=> x = 3
Ta có: 4\(^x\)+4\(^{x+3}\)=4160
\(\Rightarrow\)4\(^x\).(1+4\(^3\))=4160
\(\Rightarrow\)4\(^x\).65=4160
\(\Rightarrow\)4\(^x\)=64
\(\Rightarrow\)4\(^x\)=4\(^3\)\(\Rightarrow\)x=3