1.(1)原式=2n²-18 (2)原式=3x³+x²-3x-1
2.(1)原式=9x²-y²
(2)原式=9a²-6a+6a-4-9a²+9a=9a-4.
(3)原式=x³-y³
(4)原式=x³-x²+x+3
3.原式=x²-2x-4x+8-(x²+3x-x-3)
=x²-2x-4x+8-x²-3x+x+3
=-8x+11.
当x=-2时，原式=-8×(-2)+11=27
试卷导航1.(1)原式=2n²-18 (2)原式=3x³+x²-3x-1
2.(1)原式=9x²-y²
(2)原式=9a²-6a+6a-4-9a²+9a=9a-4.
(3)原式=x³-y³
(4)原式=x³-x²+x+3
3.原式=x²-2x-4x+8-(x²+3x-x-3)
=x²-2x-4x+8-x²-3x+x+3
=-8x+11.
当x=-2时，原式=-8×(-2)+11=27
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