## Evaluating Functions
General Explanation
The concept of FUNCTION is an important one in algebra. In the equation y=x
^{2}, the value of y is determined by the value of x, so we say that y is a function of x.
For any given value of x, we can find y by simply plugging x's value into the right hand side of the equation wherever x appears. When y is a function of x, we often show "f(x)" on the left side of the equation in place of y.
Let's consider the following function: f(x) = 9xWhat is f(x) at x=4? To evaluate this function, we simply replace every x with 4: f(4) = 9 * (4) Sample Problem
In the function below, what is f(x) at x = -7?
f(x) = 6x Solution
First replace every instance of x with -7:
f(x) = 6 * (-7)Now simplify and solve: f(x) = 6 * 49 + 35 + 1 = 294 + 35 + 1 = 330 |