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\(3^x+3^{x+1}+3^{x+2}+3^{x+3}=116\)
\(\Leftrightarrow3^x+3^x.3+3^x.3^2+3^x.3^3=116\)
\(\Leftrightarrow3^x\left(1+3+3^2+3^3\right)=116\)
\(\Leftrightarrow3^x.\left(4+9+27\right)=116\)
\(\Leftrightarrow3^x.40=116\)
\(\Leftrightarrow3^x=2,9\)
Tự làm nốt nhế:)))) _____ Nghi là sai đề
@@ Học tốt
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2^x+2^x+1+2^x+2+......+2^x+2015=2^2019-8
=>2^x(1+2+2^2+2^3+...+2^2015)=2^2019-2^3
=>2^x(2^2016-1)=2^3.(2^2016-1)
=>x=3
nhớ link nhé
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a) \(\frac{X}{2}-\frac{11}{5}=\frac{7}{8}\cdot\frac{64}{49}\)
\(\Rightarrow\frac{x}{2}-\frac{11}{5}=\frac{8}{7}\)
\(\Rightarrow\frac{x}{2}=\frac{8}{7}+\frac{11}{5}\)
\(\Rightarrow\frac{x}{2}=\frac{117}{35}\)\(\Rightarrow x=\frac{117}{35}\cdot2=\frac{234}{35}\)
b)\(\frac{x}{5}+\frac{9}{2}=\frac{6}{7}\cdot\frac{36}{49}\)
\(\Rightarrow\frac{x}{5}+\frac{9}{2}=\frac{216}{343}\)
\(\Rightarrow\frac{x}{5}=\frac{216}{343}-\frac{9}{2}=\frac{-2655}{686}\)
\(\Rightarrow x=\frac{-2655}{686}\cdot5=\frac{-13275}{686}\)
x/2 - 11/5 = 7/8 . 64/49
x/2 - 11/5 = 8/7
x/2 =8/7 + 11/5
x/2 = 117/35
x = 2.117/35 ( tính chất phân số bằng nhau)
x = 234/35
x/5 + 9/2 = 6/7 . 36/49
x/5 + 9/2 = 216/343
x/5 = 216/343 - 9/2
x/5 = -2655/686
x = 5.(-2655)/686
x = -13275/686
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x - (17 - x) = x - 7
x = x - 7 + 17 - x
x = (-7 + 17) + (x - x)
x = 10 + 0
x = 10
Vậy x = 10.
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( 4,5 - 2.x ) . 11/7 = 11/14
4,5 - 2.x = 11/14 : 11/7= 1/2
2.x = 4,5 - 1/2 =4
x = 4:2=2
\(\left(4,5-2x\right).1\frac{4}{7}=\frac{11}{14}\)
\(\Rightarrow\left(4,5-2x\right).\frac{11}{7}=\frac{11}{14}\)
\(\Rightarrow4,5-2x=\frac{11}{14}:\frac{11}{7}\)
\(\Rightarrow4,5-2x=\frac{11}{14}.\frac{7}{11}\)
\(\Rightarrow4,5-2x=\frac{1}{2}\)
\(\Rightarrow2x=4,5-\frac{1}{2}\)
\(\Rightarrow2x=4,5-0,5\)
\(\Rightarrow2x=4\)
\(\Rightarrow x=4:2\)
\(\Rightarrow x=2\)
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( x + 7 ) chia hết cho ( x + 1 )
Ta có : ( x + 7 ) = ( x + 1 ) + 6
Mà ( x + 1 ) + 6 chia hết cho x + 1 và x + 1 chia hết cho x + 1
=> 6 phải chia hết cho x + 1
=> x + 1 = { 1 ; 2 ; 3 ; 6 }
Nếu x + 1 = 1 thì x = 1 - 1 = 0 ( được )
Nếu x + 1 = 2 thì x = 2 - 1 = 1 ( được )
Nếu x + 1 = 3 thì x = 3 - 1 = 2 ( được )
Nếu x + 1 = 6 thì x = 6 - 1 = 5 ( được )
Vậy x = { 0 ; 1 ; 2 ; 5 }
\(\left(x-7\right)^{x+11}=\left(x-7\right)^{x+1}\)
\(\Rightarrow\left(x-7\right)^{x+11}-\left(x-7\right)^{x+1}=0\)
\(\Rightarrow\left(x-7\right)^{x+1}\left[\left(x-7\right)^{10}-1\right]=0\)
\(\Rightarrow\orbr{\begin{cases}\left(x-7\right)^{x+11}=0\\\left(x-7\right)^{10}-1=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x-7=0\\\left(x-7\right)^{10}=1\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=6or\text{ }x=8\end{cases}}\)