2x^5 + 4x^3 - 6x +3
Standard form means from highest exponent to lowest, with variable terms in front of any constants.
In the equation 4x^3 - 6x + 2x^5 + 3, the highest power is 5 and should be in the front. Then the second highest, 3, and the last variable term to raised to no power. The constant, 3, goes last.
This looks like: 2x^5 + 4x^3 - 6x +3.