Question

Y=f(x)=-4x find f(x) when x=0

Answer 1

Evaluating a function at a particular x value simply means to substitute every occurrence of x with the said value.

So, in your case, you have to substitute every 'x' in the function definition with '0'. We get

`f(x)=-4x \implies f(0)=-4\cdot 0 = 0`