Question

求帮忙数学

Answer 1

19. 0.37x^2y-(1/2)y^2x-(1/3)xy^2+0.13yx^2+(1/2)
=0.5x^2y-(5/6)xy^2+(1/2)
=-(5/6)xy^2+0.5x^2y+(1/2).
20. (4/3)x^3-(3/7)x^2+(2/3)x^3+5x-(4/7)x^2+3
=2x^3-x^2+5x+3
当 x=1/2 时，原式的值=2x(1/2)^3-(1/2)^2+5x(1/2)+3
=1/4-1/4+5/2+3
=11/2
=5.5.

追问

请问19题Y的升幂怎么排列，谢谢

错了，是降幂

追答

你看清了没有？我是按y的降幂排列的啊。
升幂排列如下：3+0.5x^2y-(5/6)xy^2.

追问

谢谢

Answer 2

19.
0.37x²y-1/2y²x-1/3xy²+0.13yx²+1/2
=0.5x²y-5/6xy²+1/2
=-5/6xy²+0.5x²y+1/2

20.
4/3x³-3/7x²+2/3x³+5x-4/7x²+3 x=1/2
=2x³-x²+5x+3
=2*(1/2)³-(1/2)²+5*1/2+3
=1/4-1/4+5/2+3
=11/2

追问

最后一题好像错了

Answer 3

三次方和三次方相加，二次方和二次方相加，，系数相加之后都是整数，，，这么简单的题不用心，

追答