已知A=5x^2y-3xy^2+4xy,B=7xy^2-2xy+x^2y,若A+B+2C=0,求C-A

解C=(-A-B)/2
=-2x^2y+xy-2xy^2
C-A=-7x^2y-3xy+xy^2

解：因A+B+2C=0，2(C-A)+B+3A=0
C-A=-(3A+B)/2=-[3(5x^2y-3xy^2+4xy)+7xy^2-2xy+x^2y]/2=-(16x^2y-2xy^2+10xy)/2=-8x^2y-5xy+xy^2

因A+B+2C=0，2(C-A)+B+3A=0
C-A=-(3A+B)/2=-[3(5x^2y-3xy^2+4xy)+7xy^2-2xy+x^2y]/2=-(16x^2y-2xy^2+10xy)/2=-8x^2y-5xy+xy^2 就可以做出来了

解：
∵A+B+2C=0
∴C=(-A-B)÷2
=[-5x^2y+3xy^2-4xy-(7xy^2-2xy+x^2y)]÷2
=-3x^2y-2xy^2-xy
∴C-A=-3x^2y-2xy^2-xy-(5x^2y-3xy^2+4xy)
=-8x^2y+xy^2-5xy

解:因A+B=2c 所以C=(A+B)\2
所以
C-A=(A+B)\2-A
A+B=4XY^2+2XY+6X^2Y
(A+B)\2=2XY^+XY+3X^3Y
所以(A+B)\2-A=C-A=XY^2+6XY+X^2Y

解:因为A+B+2C=0,所以A+B=-2C
5x^2y-3xy^2+4xy+7xy^2-2xy+x^2y=-2C
6x^2y+4xy^2+2xy=-2C
C=-3x^2y-2xy^2-xy
C-A=-8x^2y-5xy^2+3xy