Phân tích đa thức thành nhân tử
a,3x + 6xy + 3y - 3z
b,x + x y - x z - xyz
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\(A=3x^2+6xy+3y^2-3z^2\)
\(=3\left(x^2+2xy+y^2-z^2\right)\)
\(=3\left[\left(x^2+2xy+y^2\right)-z^2\right]\)
\(=3\left[\left(x+y\right)^2-z^2\right]\)
\(=3\left(x+y+z\right)\left(x+y-z\right)\)
a: \(=\left(x+2-y\right)\left(x+2+y\right)\)
c: \(=\left(x-y\right)^2\)
b) Ta có: \(x^3-x^2y-xy^2+y^3\)
\(=\left(x^3+y^3\right)-\left(x^2y+xy^2\right)\)
\(=\left(x+y\right)\left(x^2-xy+y^2\right)-xy\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2-2xy+y^2\right)\)
\(=\left(x+y\right)\left(x-y\right)^2\)
\(a,=4\left(x-1\right)^2\\ b,=\left(x-y\right)\left(x+y\right)+3\left(x+y\right)=\left(x+y\right)\left(x-y+3\right)\)
a, 4x2 - 8x + 4 = (2x)2 - 2.2x.2 + 2 = (2x - 2)2
b, x2 - y2 + 3x + 3y = (x2 - y2) + (3x + 3y) = (x- y). (x + y) + 3.(x + y) = (x+y).(x- y + 3)
\(x^2-2xy+y^2-z^2=\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\)
\(3x^2+6xy+3y^2-3z^2=3\left(x^2+2xy+y^2-z^2\right)=3.\left[\left(x+y\right)^2-z^2\right]=3.\left(x+y-z\right)\left(x+y+z\right)\)
\(3x^2-3xy-5x+5y=3x\left(x-y\right)-5\left(x-y\right)=\left(x-y\right)\left(3x-5\right)\)
a.\(xz+yz-5\left(x+y\right)\)
\(=z\left(x+y\right)-5\left(x+y\right)\)
\(=\left(x+y\right)\left(z-5\right)\)
b.\(3x^2-3xy-5x+5y\)
\(=3x\left(x-y\right)-5\left(x-y\right)\)
\(=\left(x-y\right)\left(3x-5\right)\)
c.\(x^2+6x-y^2-3z^2\)???Sai đề bài ...?
d.\(3x^2+6xy+3y^2-3z^2\)
\(=3\left(x^2+2xy+y^2-z^2\right)\)
\(=3\left[\left(x+y\right)^2-z^2\right]\)'
\(=3\left(x+y-z\right)\left(x+y+z\right)\)
Trả lời:
a, xz + yz - 5 ( x + y )
= ( xz + yz ) - 5 ( x + y )
= z ( x + y ) - 5 ( x + y )
= ( x + y ) ( z - 5 )
b, 3x2 - 3xy - 5x + 5y
= ( 3x2 - 3xy ) - ( 5x - 5y )
= 3x ( x - y ) - 5 ( x - y )
= ( x - y ) ( 3x - 5 )
c, x2 + 6x - y2 - 3z2
= - ( 3x2 - x2 + y2 - 6x )
d, 3x2 + 6xy + 3y2 - 3z2
= 3 ( x2 + 2xy + y2 - x2 )
= 3 [ ( x2 + 2xy + y2 ) - z2 ]
= 3 [ ( x + y )2 - z2 ]
= 3 ( x + y - z ) ( x + y + z )
a: \(27a^2b^2+18ab+3\)
\(=3\left(9a^2b^2+6ab+1\right)\)
\(=3\left\lbrack\left(3ab\right)^2+2\cdot3ab\cdot1+1^2\right\rbrack\)
\(=3\left(3ab+1\right)^2\)
b: \(5x^2-y+5xy-x\)
=5x(x+y)-(x+y)
=(x+y)(5x-1)
c: \(2x^3y^2-8x^3-12x^2y-6xy^2-y^3+x^2y^3\)
\(=x^2y^2\left(2x+y\right)-\left(2x+y\right)^3\)
\(=\left(2x+y\right)\left\lbrack x^2y^2-\left(2x+y\right)^2\right\rbrack\)
=(2x+y)(xy-2x-y)(xy+2x+y)
Bài 2:
a: \(3x^2-3xy=3x\left(x-y\right)\)
b: \(x^2-4y^2=\left(x-2y\right)\left(x+2y\right)\)
c: \(3x-3y+xy-y^2=\left(x-y\right)\left(3+y\right)\)
d: \(x^2-y^2+2y-1=\left(x-y+1\right)\left(x+y-1\right)\)
`@` `\text {Ans}`
`\downarrow`
`a,`
`3x + 6xy + 3y - 3z`
`= 3(x + 2y + y - z)`
`b,`
`x+ xy - xz - xyz`
`= x(1 + y)*(1-z)`
a: 3x^2+6xy+3y^2-3z^2
=3(x^2+2xy+y^2-z^2)
=3[(x+y)^2-z^2]
=3(x+y+z)(x+y-z)
b: x+xy-xz-xyz
=x(y+1)-xz(y+1)
=(y+1)*x*(1-z)