Question

Find f(-2), and f(1/3)
13) For f(x)=-7x-3

Answer 1

f(-2) = 11
f(1/3) = -16/3

Explanation:

When a number replaces x between the parenthesis of the function's dependent variable (y, f(x), g(x), etc.), it means we should substitute that number to find its corresponding point's y value.

In our case, "Find f(-2)" means we're asked to put -2 in place of x whenever it appears in f(x). Reminder: There's a hidden multiplication sign between constants and parameters (In our example, 7x is actually 7 * x).

`f(-2) = (-7) \cdot (-2) - 3 = 14 - 3 = 11`

f(-2) = 11

`f(\frac13) = -7 * \frac13 - 3 = -\frac73 - 3 = -\frac73 - 3 - \frac33 = -\frac73 -\frac93 = \frac{-7 -9}3 = -\frac{16}3`

f(1/3) = -16/3

Answer 2

To find f(a number), you simply replace x with that number and solve.

So for f(-2) simply replace x with -2 and then solve as if it were an algebraic equation. I showed how to do it and the answer in the picture below.

Happy solving!