Phân tích đa thức sau thành nhân tử
x2y + 5xy - 14y
x3 - 5x2 - 14x
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\(x^2y-16y=y\left(x^2-16\right)=y\left(x-4\right)\left(x+4\right)\)
\(x^2-9+5xy-15y=\left(x-3\right)\left(x+3\right)+5y\left(x-3\right)=\left(x-3\right)\left(x+3+5y\right)\)
\(a,=4\left(x-5y\right)\\ b,=5x\left(x+y\right)-\left(x+y\right)=\left(5x-1\right)\left(x+y\right)\\ c,=\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\)
\(5x^2+5xy-x-y\)
\(=5x\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(5x-1\right)\)
`5x^2 + 5xy +x +y`
`=(5x^2 + 5xy )+(x+y)`
`=5x(x+y)+(x+y)`
`=(x+y)(5x+1)`
\(5x^2+5xy+x+y\\ =5x\left(x+y\right)+\left(x+y\right)\\ =\left(x+y\right)\left(5x+1\right)\)
a: =5x(x-y)-7(x-y)
=(x-y)(5x-7)
b: =x(x+2y)+(x+2y)
=(x+2y)(x+1)
c; =(x-3)^2-9y^2
=(x-3-3y)(x-3+3y)
a
\(5x^2-5xy+7y-7x\\ =5x\left(x-y\right)+7\left(y-x\right)\\ =5x\left(x-y\right)-7\left(x-y\right)\\ =\left(5x-7\right)\left(x-y\right)\)
b
\(x^2+2xy+x+2y\\ =x\left(x+2y\right)+\left(x+2y\right)\\ =\left(x+1\right)\left(x+2y\right)\)
c
\(x^2-6x-9y^2+9\\ =x^2-6x+9-\left(3y\right)^2\\ =x^2-2.x.3+3^2-\left(3y\right)^2\\ =\left(x-3\right)^2-\left(3y\right)^2\\ =\left(x-3-3y\right)\left(x-3+3y\right)\)
\(a,a^4+a^2+1\)
\(=\left(a^2\right)^2+2a^2+1-a^2\)
\(=\left(a^2+1\right)^2-a^2\)
\(=\left(a^2+1-a\right)\left(a^2+1+a\right)\)
\(---\)
\(b,a^4+a^2-2\)
\(=a^4-a^2+2a^2-2\)
\(=a^2\left(a^2-1\right)+2\left(a^2-1\right)\)
\(=\left(a^2-1\right)\left(a^2+2\right)\)
\(=\left(a-1\right)\left(a+1\right)\left(a^2+2\right)\)
\(---\)
\(c,x^3-5x^2-14x\)
\(=x^3+2x^2-7x^2-14x\)
\(=x^2\left(x+2\right)-7x\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2-7x\right)\)
\(=x\left(x+2\right)\left(x-7\right)\)
\(a.a^4+a^2+1\)
\(=\left(a^4+2a^2+1\right)-a^2\)
\(=\left(a^2+1\right)^2-a^2\)
\(=\left(a^2+1+a\right)\left(a^2+1-a\right)\)
\(b.a^4+a^2-2\)
\(=a^4+2a^2-a^2-2\)
\(=a^2\left(a^2+2\right)-\left(a^2-2\right)\)
\(=\left(a^2+2\right)\left(a^2-1\right)\)
\(=\left(a^2+2\right)\left(a-1\right)\left(a+1\right)\)
\(c.x^3-5x^2-14x\)
\(=x^3+2x^2-7x^2-14\)
\(=x^3\left(x+2\right)-7x\left(x+2\right)\)
\(=\left(x^3-7x\right)\left(x+2\right)\)
\(=x\left(x-7x\right)\left(x+2\right)\)
a: Ta có: \(x^2-xy-3x+3y\)
\(=x\left(x-y\right)-3\left(x-y\right)\)
\(=\left(x-y\right)\left(x-3\right)\)
b: Ta có: \(5x^2+5xy-x-y\)
\(=5x\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(5x-1\right)\)
c: Ta có: \(x^2-2xy+y^2-z^2\)
\(=\left(x-y\right)^2-z^2\)
\(=\left(x-y-z\right)\left(x-y+z\right)\)
a) \(x^2+5x+5xy+25y\)
\(=x\left(x+5\right)+5y\left(x+5\right)\)
\(=\left(x+5y\right)\left(x+5\right)\)
c) \(x^2-24x-25\)
\(=x^2-25x+x-25\)
\(=x\left(x-25\right)+\left(x-25\right)\)
\(\left(x+1\right)\left(x-25\right)\)
Ta có: x2y+5xy-14y
= y(x2+5x-14)
= y(x+7)(x-2)
x3-5x2-14x
= x(x2-5x-14)
= x(x-7)(x+2)
\(x^2y+5xy-14y\)
\(=x^2y-2xy+7xy-14y\)
\(=xy\left(x-2\right)+7y\left(x-2\right)\)
\(=\left(x-2\right)\left(xy+7y\right)\)
\(x^3-5x^2-14x\)
\(=x^3-7x^2+2x^2-14x\)
\(=x^2\left(x-7\right)+2x\left(x-7\right)\)
\(=\left(x^2+2x\right)\left(x-7\right)\)
\(=x\left(x+2\right)\left(x-7\right)\)