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\(x^2-2x+2y-xy\)
\(=-2\left(x-y\right)+x\left(x-y\right)\)
\(=\left(x-y\right)\left(x-2\right)\)
Có : x^2 - x - 2
= ( x^2 - 2x ) + ( x - 2 )
= x . ( x - 2 ) + ( x - 2 )
= ( x - 2 ) . ( x + 1 )
Tk mk nha
\(x^2\) - \(x\) - 121
= (\(x^2\) - \(2.x.\frac{1}{2}\) + \(\frac{1}{4}\) ) - \(\frac{1}{4}\) - 121
= (\(x\) - \(\frac{1}{2}\) )2 - \(\frac{485}{4}\)
= (\(x\) - \(\frac{1}{2}\) - \(\frac{\sqrt{485}}{2}\) ) (\(x\) - \(\frac{1}{2}\) + \(\frac{\sqrt{485}}{2}\) )
= (\(x\) - \(\frac{1+\sqrt{485}}{2}\) ) (\(x\) - \(\frac{1-\sqrt{485}}{2}\) )
\(x^2-x-121\)
\(=\left(x^2-2.x.\frac{1}{2}+\frac{1}{4}\right)-\frac{1}{4}-121\)
\(=\left(x-\frac{1}{2}\right)^2-\frac{485}{4}\)
\(=\left(x-\frac{1}{2}-\frac{\sqrt{485}}{2}\right)\left(x-\frac{1}{2}+\frac{\sqrt{485}}{2}\right)\)
\(=\left(x-\frac{1+\sqrt{485}}{2}\right)\left(x-\frac{1-\sqrt{485}}{2}\right)\)
\(x^3-x^2-21x+45\)
\(=\left(x^3-3x^2\right)+\left(2x^2-6x\right)+\left(-15x+45\right)\)
\(=x^2\left(x-3\right)+2x\left(x-3\right)-15\left(x-3\right)\)
\(=\left(x^2+2x-15\right)\left(x-3\right)\)
\(=\left[\left(x^2-3x\right)+\left(5x-15\right)\right]\left(x-3\right)\)
\(=\left[x\left(x-3\right)+5\left(x-3\right)\right]\left(x-3\right)\)
\(=\left(x+5\right)\left(x-3\right)^2\)
\(x^4+2x^3-6x-9\)
\(=x^4-9+2x^3-6x\)
\(=\left(x^2-3\right)\left(x^2+3\right)+2x\left(x^2-3\right)\)
= \(\left(x^2-3\right)\left(x^2+3+2x\right)\)
a) x3-2x2-x+2
=x(x2-1)+2(-x2+1)
=x(x2-1)-2(x2-1)
=(x2-1)(x-2)
b)
x2+6x-y2+9
=x2+6x+9-y2
=(x+3)2-y2
=(x+3-y)(x+3+y)