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a. 2xy - x2 - y2 + 16
=(2xy-x2-y2)+16
=16-(x-y)2
=(4+x-y)(4-x+y)
b. x2 + x - 6
=x2+3x-2x-6
=x(x+3)-2(x+3)
=(x-2)(x+3)
c. x2 + 5x + 6
=x2+3x+2x+6
=x(x+3)+2(x+3)
=(x+2)(x+3)
a,\(xy+3x-7y-21\)
\(=x\left(y+3\right)-7\left(y+3\right)\)
\(=\left(y+3\right)\left(x-7\right)\)
\(b,2xy-15-6x+5y\)
\(=\left(2xy-6x\right)+\left(-15+5y\right)\)
\(=2x\left(y-3\right)-5\left(3-y\right)\)
\(=2x\left(y-3\right)+5\left(y-3\right)\)
\(=\left(y-3\right)\left(2x+5\right)\)
a) \(x^2-x-y^2-y\)
\(=\left(x^2-y^2\right)-\left(x+y\right)\)
\(=\left(x-y\right)\left(x+y\right)-\left(x+y\right)\)
\(=\left(x-y-1\right)\left(x+y\right)\)
b) \(x^2-2xy+y^2-z^2\)
\(=\left(x-y\right)^2-z^2\)
\(=\left(x-y-z\right)\left(x-y+z\right)\)
c) \(5x-5y+ax-ay\)
\(=5\left(x-y\right)+a\left(x-y\right)\)
\(=\left(5+a\right)\left(x-y\right)\)
a)x2+2xy+y2-x-y-12
\(=\left(x+y\right)^2-\left(x+y\right)-12\)
Đặt \(t=x+y\) ta có:
\(t^2-t-12=t^2+3t-4t-12\)
\(=t\left(t+3\right)-4\left(t+3\right)\)
\(=\left(t-4\right)\left(t+3\right)\)
\(=\left(x+y-4\right)\left(x+y+3\right)\)
a) 2xy2 - 6x2y + 4xy
= 2xy.(y - 3x + 2)
b) x2 - y2 - 5x + 5y
= (x+y).(x-y) - 5.(x-y)
= (x-y).(x+y-5)
c) x2 - 4y2 - 1 + 4y
= x2 - (4y2 - 4y + 1)
= x2 - [ (2y)2 - 2.2.y.1 + 12 ]
= x2 - (2y-1)2
= (x+2y-1).(x-2y+1)
a) x^4 - x^3 - x + 1
= x^3 ( x - 1 ) - ( x- 1 )
= ( x^3 - 1 )(x - 1)
= ( x- 1 )^2 (x^2 + x + 1 )
a)x4-x3-x+1
=x3(x-1)-(x-1)
=(x-1)(x3-1)
=(x-1)(x-1)(x2+x+1)
=(x-1)2(x2+x+1)
b)5x2-4x+20xy-8y
(sai đề)
\(a,y-x^2y+2xy^2-y^3=y(1-x^2+2xy-y^2) =y[1-(x^2-2xy+y^2)]=y[1-(x-y)^2] =y(1-x+y)(1+x-y) =y(x+y-1)(x-y+1) \)
a,x\(^2\)-2xy+5x-10y
=x(x-2y)+5(x-2y)
=(x-2y)(x+5)
b,x\(^2\)y+2xy\(^2\)+y\(^3\)
=x(x\(^2\)+2xy+y\(^2\))
=x(x+y)\(^2\)
c,x\(^2\)-(a+b)x+ab
=x\(^2\)-ax-bx+ab
=x(x-a)+b(x-a)
=(x-a)(x+b)