如图,有一道数学题需要您解答.
来源:学生作业帮 编辑:搜狗做题网作业帮 分类:数学作业 时间:2024/06/23 19:50:20
如图,有一道数学题需要您解答.
一正方体六个面分别标有A、B、C、D、E、F,展开如图:已知A=x^2-4xy+3y^2,B=1/2(C-A),C=3x^2-2xy+y^2,E=B-2C,若正方体相对的两个面的多项式的和都相等,求D、F.
注:x^2表示x的2次方.
![](http://img.wesiedu.com/upload/d/5a/d5ac3b904c18b453e0ec7cf5896d3fdb.jpg)
一正方体六个面分别标有A、B、C、D、E、F,展开如图:已知A=x^2-4xy+3y^2,B=1/2(C-A),C=3x^2-2xy+y^2,E=B-2C,若正方体相对的两个面的多项式的和都相等,求D、F.
注:x^2表示x的2次方.
![](http://img.wesiedu.com/upload/d/5a/d5ac3b904c18b453e0ec7cf5896d3fdb.jpg)
![如图,有一道数学题需要您解答.](/uploads/image/z/17940297-57-7.jpg?t=%E5%A6%82%E5%9B%BE%2C%E6%9C%89%E4%B8%80%E9%81%93%E6%95%B0%E5%AD%A6%E9%A2%98%E9%9C%80%E8%A6%81%E6%82%A8%E8%A7%A3%E7%AD%94.)
B+D=E+F=A+C
A=x^2-4xy+3y^2,B=1/2(C-A),
C=3x^2-2xy+y^2,E=B-2C
A+C=4x^2-6xy+4y^2
B=1/2(C-A)=1/2(3x^2-2xy+y^2-x^2+4xy-3y^2)
=1/2(2x^2+2xy-2y^2)=x^2+xy-y^2
D=A+C-B=4x^2-6xy+4y^2-(x^2+xy-y^2)
=3x^2-7xy+5y^2
E=B-2C=x^2+xy-y^2-(6x^2-4xy+2y^2)
=-5x^2+5xy-3y^2
F=A+C-E=4x^2-6xy+4y^2-(-5x^2+5xy-3y^2)
=9x^2-11xy+7y^2
A=x^2-4xy+3y^2,B=1/2(C-A),
C=3x^2-2xy+y^2,E=B-2C
A+C=4x^2-6xy+4y^2
B=1/2(C-A)=1/2(3x^2-2xy+y^2-x^2+4xy-3y^2)
=1/2(2x^2+2xy-2y^2)=x^2+xy-y^2
D=A+C-B=4x^2-6xy+4y^2-(x^2+xy-y^2)
=3x^2-7xy+5y^2
E=B-2C=x^2+xy-y^2-(6x^2-4xy+2y^2)
=-5x^2+5xy-3y^2
F=A+C-E=4x^2-6xy+4y^2-(-5x^2+5xy-3y^2)
=9x^2-11xy+7y^2