Question

计算 单项式与多项式相乘 共六道题，过程清楚，答案正确

1)(-2xy^2)(1/2xy+x^2y-3y^2)
2)2xy[(2xy)^2-3y(4xy+3x^2y)-xy^2]
3)-2^2x^2y(1/4xy^2-5y+1)
4)(5/3a^2b-10/3a^3b^2+1)(-0.2ab)
5)(3a^nb^n+1)·(2/9a^5b-5/3a^nb^2+a^2n+1·b^10-n)
6)4ab[2a^2b-3b(ab-ab^2)]

Answer 1

1)(-2xy^2)(1/2xy+x^2y-3y^2)
=-x^2y^3-2x^3y^3+6xy^4
2)2xy[(2xy)^2-3y(4xy+3x^2y)-xy^2]
=2xy[4x^2y^2-12xy^2-9x^2y^2-xy^2]
=2xy[-13xy^2-5x^2y^2]
=-26x^2y^3-10x^3y^3
3)-2^2x^2y(1/4xy^2-5y+1)
=-4x^2y(1/4xy^2-5y+1)
=-x^3y^3+20x^2y^2-4x^2y

4)(5/3a^2b-10/3a^3b^2+1)(-0.2ab)
=-1/3a^3b^2+2/3a^4b^2-1/5ab

5)(3a^nb^n+1)·(2/9a^5b-5/3a^nb^2+a^2n+1·b^10-n)
=2/3a^n+5b^n+2 -5a^2nb^n+3 + 3a^3n+1b^11

6)4ab[2a^2b-3b(ab-ab^2)]
=4ab[2a^2b-3ab^2+3ab^3]
=8a^3b^2-12a^2b^3+12a^2b^4

Answer 2

1 (-2xy^2)(1/2xy+x^2y-3y^2)
=﹣2xy²×1／2y(x＋2x²－6y)
=﹣xy³(2x²＋x－6y)
2 2xy[(2xy)^2-3y(4xy+3x^2y)-xy^2]
=2xy(4x²y²－12xy²－9x²y²－xy²)
=2xy(﹣5x²y²－13xy²)
=﹣2xy×xy²(5x＋13)
=﹣2x²y²(5x＋13)
3 题目有问题吧!
4 (5/3a^2b-10/3a^3b^2+1)(-0.2ab)
=﹣5／3(a²b－2a³b²＋1)×1／5ab
=﹣1／3ab(a²b－2a³b²＋1)
5 题目有问题吧1
6 4ab[2a^2b-3b(ab-ab^2)]
=4ab(2a²b－3ab²＋3ab³)
=4ab ×ab(2a－3b＋3b²)
=4a²b²(2a－3b＋3b²)

追问

没问题

追答

我只告诉你方法:系数和系数相乘, 相同字母的指数相加. 然后相同的整式(字母完全相同,指数也相同)和整数合并 你自己算吧!