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NN
12 tháng 12 2017
a) \(5x^2y^3-25x^3y^4+10x^3y^3\)
\(=5x^2y^3\left(1-5xy+2x\right)\)
b) \(4x^2+12x+9\)
\(=\left(2x\right)^2+2.2x.3+3^2\)
\(=\left(2x+3\right)^2\)
c) \(11x+11y-x^2-xy\)
\(=11\left(x+y\right)-x\left(x+y\right)\)
\(=\left(x+y\right)\left(11-x\right)\)
d) \(27x^2\left(y-1\right)-9x^3\left(1-y\right)\)
\(=27x^2\left(y-1\right)+9x^3\left(y-1\right)\)
\(=\left(y-1\right)\left(27x^2+9x^3\right)\)
\(=9x^2\left(y-1\right)\left(3+x\right)\)
12 tháng 12 2017
c/
\(11x+11y-x^2-xy\)
\(=\left(11x-x^2\right)+\left(11y-xy\right)\)
\(=x\left(11-x\right)+y\left(11-x\right)\)
= \(\left(11-x\right)\left(x+y\right)\)
8 tháng 12 2019
\(a,4x^2\left(5x-3y\right)-5x^2\left(4x+y\right)\)
\(=20x^3-12x^2y-20x^3-5x^2y\)
\(=-17x^2y=-17\left(-2\right)^2.\left(-3\right)=204\)
\(b,\left(x-4\right)\left(x-2\right)-\left(x-1\right)\left(x-3\right)\)
\(=x^2-6x+8-x^2+4x-3\)
\(=-2x+5=-2.74+5=143\)
NT
3
25 tháng 8 2018
\(xy+3z+xz+3y\)
\(=\left(xy+3y\right)+\left(xz+3z\right)\)
\(=y\left(x+3\right)+z\left(x+3\right)\)
\(=\left(y+z\right)\left(x+3\right)\)
\(11x-x^2+11y-xy\)
\(=x\left(11-x\right)+y\left(11-x\right)\)
\(=\left(x+y\right)\left(11-x\right)\)
25 tháng 8 2018
\(xy+3z+xz+3y\)
\(=\left(xy+xz\right)+\left(3y+3z\right)\)
\(=x\left(y+z\right)+3\left(y+z\right)\)
\(=\left(y+z\right)\left(x+3\right)\)
\(11x-x^2+11y-xy\)
\(=\left(11x+11y\right)-\left(x^2+xy\right)\)
\(=11\left(x+y\right)-x\left(x+y\right)\)
\(=\left(x+y\right)\left(11-x\right)\)
TH
17 tháng 12 2018
a) \(\dfrac{3x+5}{4x^3y}-\dfrac{5-15x}{4x^3y}\)
\(=\dfrac{3x+5-5+15x}{4x^3y}\)
\(=\dfrac{18x}{4x^3y}\)
\(=\dfrac{9}{2x^2y}\)
b) \(\dfrac{2}{x-2}+\dfrac{4}{x+2}+\dfrac{-6+5x}{4-x^2}\)
\(=\dfrac{2}{x-2}+\dfrac{4}{x+2}+\dfrac{6-5x}{x^2-4}\)
\(=\dfrac{2\left(x+2\right)}{\left(x+2\right)\left(x-2\right)}+\dfrac{4\left(x-2\right)}{\left(x+2\right)\left(x-2\right)}+\dfrac{6-5x}{\left(x+2\right)\left(x-2\right)}\)
\(=\dfrac{2\left(x+2\right)+4\left(x-2\right)+6-5x}{\left(x+2\right)\left(x-2\right)}\)
\(=\dfrac{2x+4+4x-8+6-5x}{\left(x+2\right)\left(x-2\right)}\)
\(=\dfrac{x+2}{\left(x+2\right)\left(x-2\right)}\)
\(=\dfrac{1}{x-2}\)
14 tháng 7 2017
a) \(\left(2x^2-3y^2\right)^2=\left(2x^2\right)^2-2.2x^2.3y^2+\left(3y^2\right)^2\)
\(=4x^4-12x^2y^2+9y^4\)
b) \(\left(4x-3y\right)^2-\left(4x+3y\right)^2\)
\(=\left(4x-3y-4x-3y\right)\left(4x-3y+4x+3y\right)\)
\(=-6y.8x\)
\(=-48xy\)
c) \(\left(x+\dfrac{1}{4}\right)^2=x^2+2x.\dfrac{1}{4}+\left(\dfrac{1}{4}\right)^2\)
\(=x^2+\dfrac{1}{2}x+\dfrac{1}{16}\)
d) \(\left(5x-y\right)^2\)
\(=25x^2-10xy+y^2\).
11 tháng 8 2016
a) \(=-10x^6y^7+10x^5y^6+5x^3y^5\)
b) \(=-8x^5y^3+16x^7y^2-12x^3y^4\)
Giải hpt?
Cách 1: \(\hept{\begin{cases}5x+3y=16\\4x+11y=30\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}20x+12y=64\\20x+55y=150\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}-43y=-86\\20x+115y=150\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}y=2\\20x+55.2=150\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}y=2\\x=2\end{cases}}\)
Cách 2: \(\hept{\begin{cases}5x+3y=16\\4x+11y=30\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=\frac{16-3y}{5}\\4.\frac{16-3y}{5}+11y=30\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=\frac{16-3y}{5}\\\frac{43}{5}y=\frac{86}{5}\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=\frac{16-3.2}{5}\\y=2\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=2\\y=2\end{cases}}\)