單項式-7x^2y,3x^2y^2z,-二分之一xy,5x^2y,0.5xy,-4x^3的和是()A.五次三項式B.五次四項式C.三次多項式D.

單項式-7x^2y,3x^2y^2z,-二分之一xy,5x^2y,0.5xy,-4x^3的和是()A.五次三項式B.五次四項式C.三次多項式D.

-7x^2y+3x^2y^2z+(-二分之一xy)+5x^2y+0.5xy+(-4x^3)
=-7x^2y+3x^2y^2z-0.5xy+5x^2y+0.5xy-4x^3
=-4x^3-2x^2y+3x^2y^2z選A
五次三項式