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七年级计算题(-3a-1/2b)(3/2a-3/4b)-(3/4b)^2
(3x+2y)(3x-2y)
(1-x^2)(1+x^2+x^4)
人气:125 ℃ 时间:2019-09-30 19:24:31
解答

(-3a-1/2b)(3/2a-3/4b)-(3/4b)^2

=(3a+1/2b)(3/2a-3/4b)-(3/4b)²

=9a²/2-ab/4+3ab/4-3b²/8-9b²/16

=9a²/2+(3ab/4-ab/4)-(3b²/8+9b²/16)

=9a²/2+ab/2-15b²/16





(3x+2y)(3x-2y)

=(3x)²-(2y)²

=9x²-4y²



(1-x^2)(1+x^2+x^4)

=1³-(x²)³   (立方差公式)

=1-x^6

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