2.
3.
4.
2.00
Step-by-Step Solution
Key idea: A rational function must only have integer powers of in the numerator and denominator.
Step 1: Derivative of
. This is a ratio of polynomials. (Yes)
Step 2: Derivative of
. The denominator contains a square root, so it is not a polynomial. (No)
Step 3: Derivative of
. Contains a square root. (No)
Step 4: Derivative of
. This is a polynomial, which is a rational function. (Yes)
Count: Functions 1 and 4 have rational derivatives.
Answer: 2.00