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\(\Rightarrow4\left|x-7\right|+8+2\left|x-7\right|+10=0\)
\(\Rightarrow6\left|x-7\right|+18=0\) vì \(\left|x-7\right|\ge0\) với mọi x \(\Rightarrow6\left|x-7\right|\ge0\)với mọi x\(\Rightarrow6\left|x-7\right|+18\ge18>0\)
Mà 6|x-7| +18=0 nên \(x\in\varnothing\)
\(A=3.727.3^6+3^5.3^4.3^3\)
\(A=3^7.727+3^5.3^7\)
\(A=3^7\left(727+3^5\right)\)
\(A=3^7.970\)
\(A=2121390\)
Đề : Tìm x???
\(\frac{2}{3}x+\frac{1}{4}x=\frac{-22}{27}\)
\(x\left(\frac{2}{3}+\frac{1}{4}\right)=\frac{-22}{27}\)
\(x\left(\frac{8}{12}+\frac{3}{12}\right)=\frac{-22}{27}\)
\(x.\frac{11}{12}=\frac{-22}{27}\)
\(x=\frac{-22}{27}\div\frac{11}{12}\)
\(x=\frac{-22}{27}.\frac{12}{11}\)
\(x=\frac{-8}{9}\)
Vậy \(x=-\frac{8}{9}\).
3x + 3x+1 + 3x+2 = 243
3x . 1 +3x . 31 + 3x .32 = 243
3x .(1 + 3 + 32) = 243
3x .(1 +3 + 9) = 243
3x . 13 = 243
3x = 243 : 13
Vì 243 : 13 không thuộc N => x thuộc rỗng
a) \(3^{2x-1}=243\)
\(\Leftrightarrow3^{2x-1}=3^5\)
\(\Leftrightarrow2x-1=5\)
\(\Leftrightarrow2x=5+1\)
\(\Leftrightarrow2x=6\)
\(\Leftrightarrow x=\dfrac{6}{2}\)
\(\Leftrightarrow x=3\)
Vậy \(x=3\)
b) \(\left(3^x\right)^2:3^3=\dfrac{1}{243}\)
\(\Leftrightarrow3^{2x}:3^3=\dfrac{1}{3^5}\)
\(\Leftrightarrow3^{2x}:3^3=3^{-5}\)
\(\Leftrightarrow3^{2x-3}=3^{-5}\)
\(\Leftrightarrow2x-3=-5\)
\(\Leftrightarrow2x=-5+3\)
\(\Leftrightarrow2x=-2\)
\(\Leftrightarrow x=-\dfrac{2}{2}\)
\(\Leftrightarrow x=1\)
Vậy \(x=1\)
c) \(2^{3x+2}=4^{x+5}\)
\(\Leftrightarrow2^{3x+2}=\left(2^2\right)^{x+5}\)
\(\Leftrightarrow2^{3x+2}=2^{2\left(x+5\right)}\)
\(\Leftrightarrow3x+2=2\left(x+5\right)\)
\(\Leftrightarrow3x+2=2x+10\)
\(\Leftrightarrow3x-2x=10-2\)
\(\Leftrightarrow x=8\)
Vậy \(x=8\)
d) \(3^{x+1}=9^x\)
\(\Leftrightarrow3^{x+1}=\left(3^2\right)^x\)
\(\Leftrightarrow3^{x+1}=3^{2x}\)
\(\Leftrightarrow x+1=2x\)
\(\Leftrightarrow2x-x=1\)
\(\Leftrightarrow x=1\)
Vậy \(x=1\)
3^5 = 243 nhé!
3^x=3^5
=> x = 5
Vậy x=5