Phân tích đa thức thành nhân tử
a) xy + xz + 3y + 3z
b) x2 + 2x - 3
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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) x2-xy+5y-25
= x(2-y)+ 5(y-2)
= x(2-y)-5(2-y)
= (x-5)(2-y)
\(a,=x\left(2x-y\right)+\left(2x-y\right)=\left(x+1\right)\left(2x-y\right)\\ b,=\left(a+b\right)\left(c-2\right)\\ c,=x\left(x+4y\right)+2\left(x+4y\right)=\left(x+2\right)\left(x+4y\right)\\ d,=x\left(x+2y\right)+3\left(x+2y\right)=\left(x+3\right)\left(x+2y\right)\)
`@` `\text {Ans}`
`\downarrow`
`a,`
`3x^2 + 6xy + 3y^2 - 3z`
`= 3*x^2 + 3*2xy + 3y^2 - 3z`
`= 3(x^2 + 2xy + y^2 - z)`
`b,`
`x^3 + x^2y - x^2z - xyz`
`= x(x + y)(x-z)`
b: \(x^2-6x+xy-6y\)
\(=x\left(x-6\right)+y\left(x-6\right)\)
\(=\left(x-6\right)\left(x+y\right)\)
c: \(2x^2+2xy-x-y\)
\(=2x\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(2x-1\right)\)
e: \(x^3-3x^2+3x-1=\left(x-1\right)^3\)
a) \(49-x^2-y^2+2xy=49-\left(x^2-2xy+y^2\right)=49-\left(x-y\right)^2=\left(7-x+y\right)\left(7+x-y\right)\)
b) \(\left(x-3\right)+2x\left(3-x\right)^2=\left(x-3\right)+2x\left(x-3\right)^2=\left(x-3\right)\left[1+2x\left(x-3\right)\right]=\left(x-3\right)\left(2x^2-6x+1\right)\)
\(a,xy+xz+3y+3z=\left(xy+xz\right)+\left(3y+3z\right)=x\left(y+z\right)+3\left(y+z\right)=\left(y+z\right)\left(x+3\right)\\ b,x^2+2x-3=\left(x^2-x\right)+\left(3x-3\right)=x\left(x-1\right)+3\left(x-1\right)=\left(x-1\right)\left(x+3\right)\)
a, xy+xz+3y+3z=(xy+xz) +(3y+3z)
=x. (y+z) +3.(y+z)
=(x+3).(y+z)
b, x^2+2x-3
= X^2+3x-x-3
=(x^2+3x)-(x+3)
=x. (x+3)-(x+3)
= (x-1).(x+3)