Simplify by combining like terms: 1. (5x 3 – 3x) + (8x 3 + 4x) = 2. (4y 3 + 8xy) – (3xy + 9y 3 )= 3. (5x 3 – 2y 3 ) – (5y 3 + 6x 3 )= 13x 3 + x -5y 3 +
