Đáp án:
`a)(x-1)(x+3)²`
`b)(a+1)(a²-a+1)(a²+a+1)`
`c)3(a-b+c)(x+6y)²`
Giải thích các bước giải:
`a)x³-1+5x²-5+3x-3`
`=x³+5x²+3x-(1+5+3)`
`=x³+5x²+3x-9`
`=x³+6x²-x²+9x-6x-9`
`=(x³+6x²+9x)-(x²+6x+9)`
`=x(x²+6x+9)-(x²+6x+9)`
`=(x-1)(x²+6x+9)`
`=(x-1)(x²+2.x.3+3²)`
`=(x-1)(x+3)²`
`b)a^5+a^4+a³+a²+a+1`
`=(a^5+a^4+a³)+(a²+a+1)`
`=a³(a²+a+1)+(a²+a+1)`
`=(a³+1)(a²+a+1)`
`=(a+1)(a²-a+1)(a²+a+1)`
`c)3x²(a-b+c)+36xy(a-b+c)+108y²(a-b+c)`
`=(a-b+c)(3x²+36xy+108y²)`
`=3(a-b+c)(x²+12xy+36y²)`
`=3(a-b+c)[x²+2.x.6y+(6y)²]`
`=3(a-b+c)(x+6y)²`