Question

Select the difference of (2x2 - 3x3) - (6x2 - 9x3).

Answer 1

$(2x^2-3x^2)-(6x^2-9x^3)=2x^2-3x^2-6x^2+9x^3=-4x^2+6x^3$

Answer 2

$(2x^2-3x^3)-(6x^2-9x^3) \\ =2x^2-3x^3-6x^2+9x^3 \\ =6x^3-4x^2$