Question

不论X,Y取何值代数式（X^3Y+3X^2Y-5XY^2+6Y^3)+(Y^3+2XY^2+X^2Y-2X^3)-(4X

Answer 1

（X^3+3X^2Y-5XY^2+6Y^3)+(Y^3+2XY^2+X^2Y-2X^3)-(4X^2Y-X^3-3XY^2+7Y^3)

=X^3+3X^2Y-5XY^2+6Y^3+Y^3+2XY^2+X^2Y-2X^3-4X^2Y+X^3+3XY^2-7Y^3

=(X^3-2X^3+X^3)+(3X^2Y+X^2Y-4X^2Y)+(-5XY^2+2XY^2+3XY^2)+(6Y^3+Y^3-7Y^3)

=0+0+0+0

=0

所以值是常数