If f(x) varies directly with x, and f(x) =45 when x=9, find the value of f(x) when x=3

answer choices are:

A.5
B.9
C.15
D.27

since 45 = 5*9

what is 5*3?

15 To find the value of f(x) when x = 3, we need to use the concept of direct variation. Direct variation means that when one variable increases or decreases, the other variable also increases or decreases proportionally.

In this case, we are given that "f(x) varies directly with x." This can be expressed in the form of an equation as f(x) = kx, where k is the constant of variation.

We are given that f(x) = 45 when x = 9. Using this information, we can substitute the values into the equation to solve for k:

45 = k(9)

To solve for k, divide both sides of the equation by 9:

k = 45/9
k = 5

Now that we have found the value of k, we can use it to find f(x) when x = 3. Substitute the values into the equation:

f(x) = 5x

f(3) = 5(3)
f(3) = 15

Therefore, the value of f(x) when x = 3 is 15.

The answer is (C) 15.