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nếu n E N thì 2n+1 là số lẻ lúc đó ta có:
(8x-1)2n+1 = 52n+1
<=> 8x - 1 = 5
<=> 8n = 6
<=> n = 6/8 = 3/4
a,\(2x^2-8x=0\)
\(2x\left(x-4\right)=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)
b,\(B\left(x\right)=\left(2x^2-8x\right)-\left(3x+2x^2\right)\)
\(=2x^2-8x-3x-2x^2\)
=\(-11x\)
c,\(-11x=0\)
\(\Rightarrow x=0\)
\(A\left(x\right)=2x^2-8x\)
\(\Rightarrow2x^2-8x=0\)
\(\Rightarrow x\left(2x-8\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\2x=8\Rightarrow x=4\end{matrix}\right.\)
\(B\left(x\right)=-3x+2x^2\)
\(B\left(x\right)=2x^2-3x\)
\(2x^2-3x=0\)
\(\Rightarrow x\left(2x-3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\2x=3\Rightarrow x=\dfrac{3}{2}\end{matrix}\right.\)
\(\left(3^x\right)^2=\frac{1}{243}.3^2\)
\(\left(3^x\right)^2=\frac{1}{27}\)
=>x=1,5
\(\frac{3x^2-6x+1}{x-2}=\frac{3x\left(x-2\right)+1}{x-2}=3x+\frac{1}{x-2}\)
Vì \(x\inℤ\)\(\Rightarrow3x\inℤ\)
\(\Rightarrow\)Để \(\frac{3x^2-6x+1}{x-2}\inℤ\)thì \(\frac{1}{x-2}\inℤ\)
\(\Rightarrow1⋮x-2\)\(\Rightarrow x-2\inƯ\left(1\right)=\left\{-1;1\right\}\)
\(\Rightarrow x\in\left\{1;3\right\}\)
Vậy \(x\in\left\{1;3\right\}\)
a) Ta có: \(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(5x+7\right)\left(3x-1\right)\)
\(\Leftrightarrow3x\left(5x+1\right)+2\left(5x+1\right)=5x\left(3x-1\right)+7\left(3x-1\right)\)
\(\Leftrightarrow15x^2+3x+10x+2=15x^2-5x+21x-7\)
\(\Leftrightarrow15x^2-15x^2+3x+10x+5x-21x=-7-2\)
\(\Leftrightarrow-3x=-9\)
\(\Leftrightarrow x=3\)
Vậy x = 3
b) Ta có: \(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\Leftrightarrow\left(x+1\right)\left(x+3\right)=\left(2x+1\right)\left(0,5x+2\right)\)
\(\Leftrightarrow x\left(x+3\right)+\left(x+3\right)=2x\left(0,5x+2\right)+\left(0,5x+2\right)\)
\(\Leftrightarrow x^2+3x+x+3=x^2+4x+0,5x+2\)
\(\Leftrightarrow x^2-x^2+3x+x-4x-0,5x=2-3\)
\(\Leftrightarrow-0,5x=-1\Leftrightarrow x=2\)
Vậy x = 2
(5x+1)2=36/49
(5x+1)2=\(\left(\frac{6}{7}\right)^2\)
5x+1=6/7
5x=-1/7
x=-1/35
5x=125
5x=53
x=3