Đáp án:
`8)7(x-y)(2x-2y-3)`
`9)8x(a-b)(x+3ay-3by)`
`10)2x(a+b+c)(x-4y)`
`11)3xy(a+b)(2ax+2bx-3y+1)`
`12)(x-y)^2(1+x-y)`
`13)(x-y)^2(x^2-2xy+y^2+1)`
`14)(3x-2y)^4(1-3x+2y)`
Giải thích các bước giải:
`8)14(x-y)^2+21(y-x)=14(x-y)^2-21(x-y) =7(x-y)[2(x-y)-3]=7(x-y)(2x-2y-3)`
`9)8(a-b)x^2+24(a-b)^2xy=8x(a-b)[x+3(a-b)y]=8x(a-b)(x+3ay-3by)`
`10)2x^2(a+b+c)-4xy(a+b+c)=2x(a+b+c)(x-4y)`
`11)6(a+b)^2x^2y+3(a+b)xy-18(a+b)xy^2=3xy(a+b)[2x(a+b)+1-3y]=3xy(a+b)(2ax+2bx-3y+1)`
`12)(x-y)^2-(y-x)^3=(x-y)^2+(x-y)^3=(x-y)^2(1+x-y)`
`13)(x-y)^4+(y-x)^2=(x-y)^4+(x-y)^2=(x-y)^2[(x-y)^2+1]=(x-y)^2(x^2-2xy+y^2+1)`
`14)(3x-2y)^4+(2y-3x)^5=(3x-2y)^4-(3x-2y)^5=(3x-2y)^4[1-(3x-2y)]=(3x-2y)^4(1-3x+2y)`
