Question

[Lê Quang Dũng]

1 Rút gon các biểu thức sau:

a) (y-3)(y+3) ; b) (m+n)(m^2-mn+n^2) ; c) (2-a)(4+2a+a^2)

d) (a-b-c)^2-(a-b+c)^2 ; e) (a-x-y)^3-(a+x-y)^3

f) (1+x+x^2)(1-x)(1+x)(1-x+x^2)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(=y^2-9\)

b: \(=m^3+n^3\)

c: \(=8-a^3\)

d: \(=\left(a-b-c-a+b-c\right)\left(a-b-c+a-b+c\right)\)

\(=-2c\cdot\left(2a-2b\right)\)

\(=-4ac+4bc\)

f: \(=\left(1-x^3\right)\left(1+x^3\right)=1-x^6\)