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【计算题(写过程)(1)(3x+4)(3x-4)-9(x-2)(x-3)(2)(1-2x)(1+2x)(1+4x²)(3)(x+y-2)(x+y+2)】
题目内容:
计算题(写过程)
(1)(3x+4)(3x-4)-9(x-2)(x-3)
(2)(1-2x)(1+2x)(1+4x²)
(3)(x+y-2)(x+y+2)优质解答
(1)(3x+4)(3x-4)-9(x-2)(x-3)
=9x²-16-9(x²-5x+6)
=9x²-16-9x²+45x-54
=45x-70
(2)(1-2x)(1+2x)(1+4x²)
=(1-4x²)(1+4x²)
=1-16x^4
(3)(x+y-2)(x+y+2)
=[(x+y)-2][(x+y)+2]
=(x+y)²-2²
=x²+2xy+y²-4
(1)(3x+4)(3x-4)-9(x-2)(x-3)
(2)(1-2x)(1+2x)(1+4x²)
(3)(x+y-2)(x+y+2)
优质解答
=9x²-16-9(x²-5x+6)
=9x²-16-9x²+45x-54
=45x-70
(2)(1-2x)(1+2x)(1+4x²)
=(1-4x²)(1+4x²)
=1-16x^4
(3)(x+y-2)(x+y+2)
=[(x+y)-2][(x+y)+2]
=(x+y)²-2²
=x²+2xy+y²-4
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