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多项式的乘法都要过程(x+2)(x-8)=(a的2方+3)(a的2方+9)(2a+b)(3a-b)(2x+3y)(1/2

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多项式的乘法
都要过程(x+2)(x-8)=
(a的2方+3)(a的2方+9)
(2a+b)(3a-b)
(2x+3y)(1/2x-1/3y)
(3a-4)(3a+4)
(1-4x的2方)(1+4x的2方)
(x-3)(x-5)-3(x-1)(x+3)
(a+2b-3)(a-2b+3)
(2x-y)(3x-2y)+(y-x)(2x-5y)
(2x-1)(2x+1)(x的2方+x+1)
这些我都做好了
多项式的乘法都要过程(x+2)(x-8)=(a的2方+3)(a的2方+9)(2a+b)(3a-b)(2x+3y)(1/2
最好了还问,想对答案?
(x+2)(x-8)
=x^2-8x+2x-16
=x^2-6x-16
(a^2+3)(a^2+9)
=a^4+3a^2+9a^2+27
=a^4+12a^2+27
(2a+b)(3a-b)
=6a^2-2ab+3ab-b^2
=6a^2+ab-b^2
(2x+3y)(1/2x-1/3y)
=x^2-2/3xy+3/2xy-y^2
=x^2+5/6xy-y^2
(3a-4)(3a+4)
=(3a)^2-4^2
=9a^2-16
(1-4x^2)(1+4x^2)
=1^2-(4x^2)
=1-16x^4
(x-3)(x-5)-3(x-1)(x+3)
=x^2-3x-5x+15-3(x^2-x+3x-3)
=x^2-8x+15-3x^2-6x+9
=-2x^2-14x+24
(a+2b-3)(a-2b+3)
=[a+(2b-3)][a-(2b-3)]
=a^2-(2b-3)^2
=a^2-(4b^2-12b+9)
=a^2-4b^2+12b-9
(2x-y)(3x-2y)+(y-x)(2x-5y)
=6x^2-4xy-3xy+2y^2+2xy-5y^2-2x^2+5xy
=4x^2-3y^2
(2x-1)(2x+1)(x^2+x+1)
=(4x^2-1)(x^2+x+1)
=4x^4+4x^3+4x^2-x^2-x-1
=4x^4+4x^3+3x^2-x-1