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计算(x²+x+6)(x²-x+6)
还有一道 (x³+2)²-2(x+2)(x-2)(x²+4)-(x²-2)²,其中x=-1/2
人气:136 ℃ 时间:2020-02-05 15:57:51
解答
(x²+x+6)(x²-x+6)
=[(x²+6)+x][(x²+6)-x]
=(x²+6)²-x²
=x^4+12x²+36-x²
=x^4+11x²+36
(x³+2)²-2(x+2)(x-2)(x²+4)-(x²-2)²
=x^6+4x³+4-2(x²-4)(x²+4)-(x^4-4x²+4)
=x^6+4x³+4-2(x^4-16)-x^4+4x²-4
=x^6+4x³+4-2x^4+32-x^4+4x²-4
=x^6-3x^4+4x³+4x²+32
将x=-1/2代入,得:
原式=1/64-3×(1/16)+4×(-1/8)+4×(1/4)+32
=1/64-3/16-1/2+1+32
=32+21/64
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