Thực hiện phép tính:
\(\frac{1-2x}{2x}+\frac{2x}{2x-1}+\frac{1}{2x-4x^2}\)
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Bài 1 :
\(\frac{x^3-9x}{15-5x}=\frac{-x^2-3x}{5}\left(ĐKXĐ:x\ne3\right)\)
\(\Leftrightarrow5\left(x^3-9x\right)=-\left(x^2+3x\right)\left(15-5x\right)\)
\(\Leftrightarrow5x^3-45x=5x^3-45\) ( luôn đúng )
Do đó : \(\frac{x^3-9x}{15-5x}=\frac{-x^2-3x}{5}\left(x\ne3\right)\)
P/s : Bài này thì xét tích chéo của hai số thôi nhé @
1. 2x2y(2x2+3x+3)
= 4x4y +6x3y+6x2y
2) ( 4x2y + 6xy2 - 2x )1/2xy2
= 2x3y3 +3x2y4-x2y2
a: \(=-\left(10x^2+15x-8x-12\right)=-10x^2-7x+12\)
CÂU 1:thực hiện phép tinh.
2x(3x^2-7x+2)
(x-2)(3x^2+2x+4)
(3x^2y^2+6x^2y^3-12xy)÷3xy
X^2/x-2+4-4x/x-2
\(2x\left(3x^2-7x+2\right)\)
\(=6x^3-14x^2+4x\)
\(\left(x-2\right)\left(3x^2+2x+4\right)\)
\(=3x^3+\left(-4x^2\right)+\left(-8\right)\)
\(\left(3x^2y^2+6x^2y^3-12xy\right)\div3xy\)
\(=xy+2xy-4\)
x^2/x-2+4-4x/x-2 ???
\(\left(\dfrac{2x-1}{2x+1}-\dfrac{2x+1}{2x-1}\right):\dfrac{8x}{8x-4}\)
\(=(\dfrac{\left(2x-1\right)^2}{4x^2-1}-\dfrac{\left(2x+1\right)^2}{4x^2-1}):\dfrac{8x}{4\left(2x-1\right)}\)
\(=\left(\dfrac{4x^2-4x+1}{4x^2-1}-\dfrac{4x^2+4x+1}{4x^2-1}\right):\dfrac{8x}{4\left(2x-1\right)}\)
\(=\dfrac{4x^2-4x+1-4x^2-4x-1}{4x^2-1}:\dfrac{8x}{4\left(2x-1\right)}\)
\(=\dfrac{-8x}{4x^2-1}:\dfrac{8x}{4\left(2x-1\right)}\)
\(=\dfrac{-8x.4\left(2x-1\right)}{8x\left(2x-1\right)\left(2x+1\right)}\)
\(=\dfrac{-8x.4}{8x\left(2x+1\right)}\)
\(=\dfrac{-4}{2x+1}\)
ĐKXĐ : \(x\ne\pm\frac{1}{2}\)
\(E=\left(\frac{\left(4x^2+2x\right)\left(1+4x^2\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}-\frac{\left(4x^2-2x\right)\left(1-4x^2\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}\right):\left(\frac{\left(1+2x\right)\left(1+2x\right)}{\left(1-2x\right)\left(1+2x\right)}-\frac{\left(1-2x\right)\left(1-2x\right)}{\left(1+2x\right)\left(1-2x\right)}\right)\)
\(E=\left(\frac{16x^4+8x^3+4x^2+2x+16x^4-8x^3-4x^2+2x}{1-16x^4}\right):\left(\frac{1+2x+x^2-1+2x-x^2}{1-4x^2}\right)\)
\(E=\frac{32x^4+4x}{1-16x^4}:\frac{4x}{1-4x^2}\)
\(E=\frac{4x\left(8x^3+1\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}.\frac{1-4x^2}{4x}\)
\(E=\frac{8x^3+1}{1+4x^2}\)
Study well
E=\(\left(\frac{4x^2+2x}{1-4x^2}-\frac{4x^2-2x}{1+4x^2}\right):\left(\frac{1+2x}{1-2x}-\frac{1-2x}{1+2x}\right)\)
E=\(\left(\frac{\left(4x^2+2x\right)\left(1+4x^2\right)-\left(4x^2-2x\right)\left(1-4x^2\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}\right):\)\(\left(\frac{\left(1+2x\right)^2-\left(1-2x\right)^2}{\left(1-2x\right)\left(1+2x\right)}\right)\)
E=\(\frac{4x^2+16x^4+2x+8x^3-\left(4x^2-16x^4-2x+8x^3\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}:\)\(\left(\frac{\left(1+4x+4x^2\right)-\left(1-4x+4x^2\right)}{\left(1-2x\right)\left(1+2x\right)}\right)\)
E=\(\frac{4x^2+16x^4+2x+8x^3-4x^2+16x^4+2x-8x^3}{\left(1-4x^2\right)\left(1+4x^2\right)}:\)\(\left(\frac{1+4x+4x^2-1+4x-4x^2}{\left(1-2x\right)\left(1+2x\right)}\right)\)
E=\(\frac{16x^4+2x+16x^4+2x}{\left(1-4x^2\right)\left(1+4x^2\right)}:\)\(\left(\frac{8x}{\left(1-2x\right)\left(1+2x\right)}\right)\)
E=\(\frac{32x^4+8x}{\left(1-4x^2\right)\left(1+4x^2\right)}.\frac{1-4x^2}{8x}\)
E=\(\frac{8x\left(4x^3+1\right)}{\left(1-4x^2\right)\left(1+4x^2\right)}.\frac{1-4x^2}{8x}\)
E=\(\frac{4x^3+1}{1+4x^2}\)
\(=\dfrac{4x\left(x+1\right)+1}{4x^2}\cdot\left(\dfrac{-\left(2x-1\right)}{2x+1}+\dfrac{1}{\left(2x+1\right)\left(2x-1\right)}\cdot\dfrac{\left(2x-1\right)^2}{2x+1}\right)-\dfrac{1}{2x}\)
\(=\dfrac{\left(2x+1\right)^2}{4x^2}\cdot\left(\dfrac{-\left(2x-1\right)}{2x+1}+\dfrac{2x-1}{\left(2x+1\right)^2}\right)-\dfrac{1}{2x}\)
\(=\dfrac{\left(2x+1\right)^2}{4x^2}\cdot\dfrac{-\left(2x-1\right)\left(2x+1\right)+2x-1}{\left(2x+1\right)^2}-\dfrac{1}{2x}\)
\(=\dfrac{-4x^2+1+2x-1}{4x^2}-\dfrac{1}{2x}\)
\(=\dfrac{-4x^2+2x}{4x^2}-\dfrac{1}{2x}\)
\(=\dfrac{-2x\left(2x-1\right)}{2x\cdot2x}-\dfrac{1}{2x}\)
\(=\dfrac{-2x+1-1}{2x}=\dfrac{-2x}{2x}=-1\)