factorization..有2條,好急!!

1. 跟據你話[第1題個27同8係2同3既3次方],so你打錯左條數- -"
27x^3-8y^3
=3^3x^3-2^3y^3.......你知道27同8係2同3既3次方,直接寫打泥就ok
=(3x)^3-(2y)^3........你要知道(ab)^3=a^3b^3
=(3x-2y)[(3x)^2+(3x)(2y)+(2y)^2].....你要知道a^3-b^3=(a-b)(a^2+ab+b^2)
=(3x-2y)(9x^2+6xy+4y^2)
最詳細既@@"

2. 同上面既一樣
(x+y)^3-(x-y)^3
=[x+y-(x-y)][(x+y)^2+(x+y)(x-y)+(x-y)^2].....用a^3-b^3=(a-b)(a^2+ab+b^2)
=(2y)[(x^2+2xy+y^2)+(x^2-y^2)+x^2-2xy+y^2]......留心(x+y)(x-y)=x^2-y^2
=2y(3x^2+y^2)
搞掂@0@

Q!. I think the question is 27x^3 - 8y^3. If this is correct, then
27x^3 - 8y^3 = (3x)^3 - (2y)^3
=(3x - 2y)[(3x)^2 + (3x)(2y) + (2y)^2]
= (3x - 2y)(9x^2 + 6xy + 4y^2).
Q2.
=[(x+y) - (x-y)][(x+y)^2 +(x+y)(x-y) + (x-y)^2]
= 2y[(x+y)^2 + x^2 - y^2 + (x-y)^2]
= 2y[x^2 + 2xy + y^2 + x^2 - y^2 + x^2 - 2xy + y^2]
= 2y(3x^2 + y^2).