求解题:多项式相乘
发布网友
发布时间：2023-11-13 21:01
共1个回答
热心网友
时间：2024-12-05 05:21
=(6x^2+13x+6)(x-2)
=6x^3+x^2-20x-12
(2) (1/2xy + 4/3x^2)(-2/3yx^2 - 3/4xy^2+ 7/6x^2）
=14/9x^4+7/12x^3y-8/9x^4y-4/3x^3y^2-3/8x^2y^3
(3) 解方程：-x(x+6)=3x-(x-3)(x+4)
解: -x^2-6x=3x-x^2-x+12
-8x=12
x=-3/2
(4)已知：f(y)=1/2·a^4·y^2 - 1/3a^3·y^3-1/4a^2·y^4，
求：f(y)·（-2/3a的平方·y的平方）
f(y)(-2/3a^2y^2）=(1/2·a^4·y^2 - 1/3a^3·y^3-1/4a^2·y^4)(-2/3a^2y^2)
=-1/3a^6y^4+2/9a^5y^5+1/6a^4y^6
(5)化简：3x的平方·y - [xy·(3x+2y) - 2y·(xy-y)]，并求当 x=5 , y=-2时的值
3x^2y - [xy(3x+2y)-2y(xy-y)]
=3x^2y-3x^2y-2xy^2+2xy^2-2y^2
=-2y^2
当 y=-2时
-2y^2=-2(-2)^2
=-8
