# Thread: Find Value of c

1. ## Find Value of c

A certain function has the form f(x) = ax + b
where a and b ≠ 0.

If f(5) = 1, f(-3) = 25 and f(c) = 0, what is the value of c?

2. Originally Posted by sharkman
A certain function has the form f(x) = ax + b
where a and b ≠ 0.

If f(5) = 1, f(-3) = 25 and f(c) = 0, what is the value of c?
$f(5) = 5a + b = 1$

$f(-3) = -3a + b = 25$

Solve for a and b simultaneously

$f(c) = ac + b = 0$

Sub in the now known values of a and b to find c.

3. ## How...

Originally Posted by e^(i*pi)
$f(5) = 5a + b = 1$

$f(-3) = -3a + b = 25$

Solve for a and b simultaneously

$f(c) = ac + b = 0$

Sub in the now known values of a and b to find c.
How did you determine that this is a system of two equations?

4. Originally Posted by sharkman
How did you determine that this is a system of two equations?
Two values for f(x) were given and there are also two constants in f(x)