$$1.5x(3x^2 - 5)(2x^2 + 3) = 1.5x(3x^2 cdot 2x^2 + 3x^2 cdot 3 - 5 cdot 2x^2 - 5 cdot 3) = 1.5x(6x^4 + 9x^2 - 10x^2 - 15) = 1.5x(6x^4 - x^2 - 15) = 1.5x cdot 6x^4 - 1.5x cdot x^2 - 1.5x cdot 15 = 9x^5 - 1.5x^3 - 22.5x$$