Subtract
(1.5x^3+4.8x^2-3.7x)(-4.3x^3-4.5x^2+32)
If this is your problem,
(1.5x^3 + 4.8x^2 - 3.7x) - (-4.3x^3 - 4.5x^2 + 32)
5.8 x^3 + 9.3 x^2 - 3.7 x - 32
(1.5x^3+4.8x^2-3.7x)(-4.3x^3-4.5x^2+32)
(1.5x^3 + 4.8x^2 - 3.7x) - (-4.3x^3 - 4.5x^2 + 32)
5.8 x^3 + 9.3 x^2 - 3.7 x - 32