计算:(1).(a+b)(a²-b²) (2).(2x-1)(4x²+2x+1) (3).(x-1)(x²+2)
问题描述:
计算:(1).(a+b)(a²-b²) (2).(2x-1)(4x²+2x+1) (3).(x-1)(x²+2)
答
(1).(a+b)(a²-b²)
=a(a²-b²)+b(a²-b²)
=a³-ab²+a²b-b³
(2).(2x-1)(4x²+2x+1)
=2x(4x²+2x+1)-(4x²+2x+1)
=8x³+4x²+2x-4x²-2x-1
=8x³-1
(3).(x-1)(x²+2)
=x(x²+2)-(x²+2)
=x³+2x-x²-2