Introduction to Biochemistry - Quiz 2.4.2

Obviously, it is [S], this is something we have control.

At the beginning of the reaction, the concentration of product is so low that the reverse reaction from product to enzyme substrate complex is negligible.

According to the michaelis and menten equation, it is

$ V_0 = \frac{V_{max}[S]}{k_m + [S]} = \frac{V_{max}k_m}{k_m + k_m} = \frac{V_{max}}{2} $.

Therefore the answer is:

Initial velocity is equal to one-half $ V_{max} $.

Despite the long question, this question is stupid, it is really just substituting the given equation.