Evaluate a Function
What are Functions? - How it Works - Video
Example 1
Example 1:
Here we have f(x) = -x2 - x + 5. We want to find f(-2), f(0), and f(3).
Let's substitute our input values: -2, 0, and 3 for x so we can find the y-values.
f(-2) = -x2 - x + 5
f(-2) = -(-2)2 - (-2) + 5
f(-2) = -1 * (-2)2 - (-2) + 5
f(-2) = -1 * 4 - (-2) + 5
f(-2) = -4 - (-2) + 5
f(-2) = -4 + 2 + 5
f(-2) = 3
Substituted the input value, -2.
Rewrote -(-2)2 .
Squared the number.
Multiplied.
Dropped the parenthesis and changed the sign
Added.
f(0) = -x2 - x + 5
f(0) = -(0)2 - (0) + 5
f(0) = -1 * (0)2 - (0) + 5
f(0) = -1 * 0 - (0) + 5
f(0) = 0 - (0) + 5
f(0) = 0 - 0 + 5
f(0) = 5
Substituted the input value, -2.
Rewrote -(0)2 .
Squared the number.
Multiplied.
Dropped the parenthesis.
Added.
f(3) = -x2 - x + 5
f(3) = -(3)2 - (3) + 5
f(3) = -1 * (3)2 - (3) + 5
f(3) = -1 * 9 - (3) + 5
f(3) = -9 - (3) + 5
f(3) = -9 - 3 + 5
f(3) = -7
Substituted the input value, -2.
Rewrote -(0)2 .
Squared the number.
Multiplied.
Dropped the parenthesis.
Added.