1.计算(a^2+a+1)(a^2-a+1) 2.计算(x-y)(x+y)+(3x-2y)(2x+y)-x(6x-y)

题目

1.计算(a^2+a+1)(a^2-a+1) 2.计算(x-y)(x+y)+(3x-2y)(2x+y)-x(6x-y)

答案

1.
(a²+a+1)(a²-a+1)
=[(a²+1)+a][(a²+1)-a]
=(a²+1)²-a²
=a^4+2a²+1-a²
=a^4+a²+1
2.
(x-y)(x+y)+(3x-2y)(2x+y)-x(6x-y)
=x²-y²+6x²-xy-2y²-6x²+xy
=x²-3y²