Answer:
y = -2x^2 - 8x + 0
Explanation:
By "standard form," I assume you mean "y = ax^2 + bx + c."
Your f(x)= -2x^2-8x has no constant term. But that's OK!
In standard form, then, you have y = -2x^2 - 8x + 0, or just y = -2x^2 - 8x.
Recognizing that this is a quadratic function, we can write:
a = -2, b = -8 and c = 0.
If this isn't the "standard form" that you had in mind, please share your version of "standard form."