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\(\frac{\left(x-3\right)^3}{3x^2}:\frac{x^2-6x+9}{6x}\)
\(=\frac{\left(x-3\right)^3}{3x^2}.\frac{6x}{\left(x-3\right)^2}\)
\(=\frac{2\left(x-3\right)}{x}\)
\(=\frac{2x-6}{x}\)
#H
Trả lời:
\(\frac{\left(x-3\right)^3}{3x^2}:\frac{x^2-6x+9}{6x}\)
\(=\frac{\left(x-3\right)^3}{3x^2}.\frac{6x}{x^2-6x+9}\)
\(=\frac{\left(x-3\right)^3}{3x^2}.\frac{6x}{\left(x-3\right)^2}\)
\(=\frac{\left(x-3\right)^3.6x}{3x^2.\left(x-3\right)^2}\)
\(=\frac{2\left(x-3\right)}{x}\)
a: \(=\dfrac{2\left(x-4\right)\left(x+4\right)}{x-4}=2x+8\)
b: \(=\dfrac{5x+2}{3xy^2}\cdot\dfrac{x^2y}{2\left(5x+2\right)}=\dfrac{x}{6y}\)
a) \(\frac{-3}{4}.\left(4x-8\right)\)
\(=\frac{-3}{4}.4x-\frac{-3}{4}.8\)
\(=-3x+6\)
b tương tự
\(2x^2\left(3x-5x^3\right)+10x^5-5x^3\)
\(=\left(6x^3-10x^5\right)+10x^5-5x^3\)
\(=6x^3-10x^5+10x^5-5x^3\)
\(=\left(6x^3-5x^3\right)-\left(10^5-10^5\right)\)
\(=x^3\)
\(\left(x+2\right)\left(x^2-2x+4\right)+\left(x-4\right)\left(x+2\right)\)
\(=\left(x+2\right)\left[\left(x^2-2x+4\right)\right]+\left(x-4\right)\)
\(=\left(x+2\right)\left(x^2-2x+4+x-4\right)\)
\(=\left(x+2\right)\left[\left(x-2x\right)+\left(4-4\right)+x^2\right]\)
\(=\left(x+2\right)\left(-1+x\right)\)
\(=-x+x^2+\left(-2\right)+2x\)
\(=x+x^2+\left(-2\right)\)
a) Đề:............
= 6x4 - 15x3 - 12x2
b) Đề:...........
= x2 + 2x + 1 + x2 + 3x - 2x - 6 - 4x
= 2x2 - x - 5
\(=x^4-xy+xy+x^2y-x^4-x^2y+3xy-xy.\)
\(=2xy\)
Thay x = 1/4 , y = - 2005 ta được: 2xy = 2.1/4 . ( - 2005 ) = -2005/2
\(\frac{4}{x+2}+\frac{3}{x-2}+\frac{-5x-2}{x^2-4}\)ĐK : \(x\ne\pm2\)
\(=\frac{4\left(x-2\right)+3\left(x+2\right)-5x-2}{\left(x+2\right)\left(x-2\right)}=\frac{4x-8+3x+6-5x-2}{\left(x+2\right)\left(x-2\right)}\)
\(=\frac{2x-4}{\left(x+2\right)\left(x-2\right)}=\frac{2\left(x-2\right)}{\left(x+2\right)\left(x-2\right)}=\frac{2}{x+2}\)