I
(12y2 + 17y - 4) + (9y2 - 13y + 3)
21y2 + 4y - 1
(2x3 + 7x2 + x) + (2x2 - 4x - 12)
2x3 + 9x2 - 3x - 12
(-3m2 + m) + (4m2 + 6m)
m2+ 7m
(7z2 + 4z - 1) + (2z2 - 6z + 2)
9z2 - 2z + 1
(3a2 + 2a - 2) - (a2 - 3a + 7)
2a2 + 5a - 9
(5x2 - 2x - 1) - (3x2 - 5x + 7)
2x2 + 3x - 8
-(3z2 + 4z) - (6z2 - 2)
-9z2 - 4z + 2
(6x3 - 4x2 + x - 9) - (3x2 + 7x + 3)
6x3 - 7x2 - 6x - 12
(2x2 + 1) + (x2 - 2x + 1)
3x2 - 2x + 2
(-s2 - 3) - (2s2 + 10s)
-3s2 - 10s - 3
(5 - 9a3 ) + (4a2 + 6a - 3)
-9a3 + 4a2 + 6a + 2
(3x2 - x) + 5x3 + (-4x3 + x2 - 8)
x3 + 4x2 - x - 8
-10(u + v) + 8(u - 1) - 3(u + 6)
-5u - 10v - 14
7x -[2(x2 - z) + 4x2 - 7z] + 6z2
-6x2 + 7x + 6z2 + 9z
3(x2 - 2x + 3) - 4(4x + 1) - (3x2 - 2x)
-20x + 9