Help pls!! The functionſ is defined by f(x) = x(x + 3). If f(a) = 40 and a > 0, what is the value of a ?
A) 3
B) 5
C) 7
D) 8

B

Step-by-step explanation:

We are given the function:

We are given that f(a) = 40 and a > 0 and we want to determine the value of a.

Substitute:

Distribute:

Subtract 40 from both sides:

We can factor using 8 and -5. Hence:

By the Zero Product Property:

Solve for each case:

Since a > 0, we can eliminate the first solution. Hence:

Our answer is B.