计算:(1)(n+1)(n+3)(n+5) ;(2)-5x(-x²+2x+1)-(2x+3)(5-x²
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计算:(1)(n+1)(n+3)(n+5) ;(2)-5x(-x²+2x+1)-(2x+3)(5-x²)
要详细过程
要详细过程
(1)
(n+1)(n+3)(n+5)
=(n²+4n+3)(n+5)
=n⁴+5n+4n²+20n+3n+15
=n⁴+4n²+28n+15
(2)-5x(-x²+2x+1)-(2x+3)(5-x²)
=5x³-10x²-5x-(10x-2x³+15-3x²)
=5x³-10x²-5x-10x+2x³-15+3x²
=5x³+2x³+3x²-10x²-5x-10x-15
=7x³-7x²-15x-15
(n+1)(n+3)(n+5)
=(n²+4n+3)(n+5)
=n⁴+5n+4n²+20n+3n+15
=n⁴+4n²+28n+15
(2)-5x(-x²+2x+1)-(2x+3)(5-x²)
=5x³-10x²-5x-(10x-2x³+15-3x²)
=5x³-10x²-5x-10x+2x³-15+3x²
=5x³+2x³+3x²-10x²-5x-10x-15
=7x³-7x²-15x-15
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