Add polynomials
100

(2x+5y)+(3x-2y)

=5x+3y 

200

(3x+3x-4x+5)+(x-2x2+x-4)

=4x3+x-3x+1

300

(7x2 -x-4)+(x2 -2x-3)+(-2x+3x+5)

=6x2 -2

400

(x3+5x2 -2x)+(x3+3x-6)+(-2x2+x-2)

=2x2+3x2+2x-8

500

(x3+3x2+5x-4)-(3x-8x-5x+6)

=-2x3+11x2+10x-10