suma y resta de polimonios

1: (7x²+2)-(3x²-5)=  4x²+7

2: (8x²-x)-(7x²+3x)= 1x²-4x

3: ( 3x²-2x-1)-(4x²+2x+5)=-1x²-4x-6

4: (-3x+x²-1)-(5x+1-3x²)=4x²-3x-2

5: (-1+7x²-2x)-(5x+3x²-7)=4x²-7x+6

6: (7x³-x²+x-1)-(2x²+3x+6)=7x³-3x²-2x-7

7: (5x²-2x+5)-(3x³-x²+5)= 3x+6x²-2x+0

8: (3x²-x-7)-(5x³+5-x²+2x)=5x³+4x²-3x-12

9: (6x³-2x²-3x+1)-(-x³-x²-5x+7)=  7x³-1x²+2x-6

10: ( x-3x²+x³+9)-(-8+7x-x²+x³)=0x³-2x²-6x+17