Suppose a functionfis defined as follows: You start with a real numberxand add 3. Then you square the resulting number. Finally you multiply the resulting number by 4. Which of the following formulas representsf(x)?

a. f(x) = 4(x2 + 3)

b. f(x) = 4x2 + 3

c. f(x) = (4x + 3)2

d. f(x) = 4(x + 3)2