Evaluating a Function
Evaluating a function is a Grade 7 math skill from Yoshiwara Intermediate Algebra where students substitute a specific input value into a function rule and compute the resulting output. This applies to algebraic expressions, tables, and graphs.
Key Concepts
Property Finding the value of the output variable that corresponds to a particular value of the input variable is called evaluating the function . To evaluate a function described by an equation, we substitute the given input value into the equation to find the corresponding output, or function value.
Examples Given the function $f(x) = 5x 2$, to evaluate $f(3)$, we substitute $x=3$ to get $f(3) = 5(3) 2 = 15 2 = 13$.
For the function $g(t) = t^2 + 10$, evaluating at $t= 4$ means calculating $g( 4) = ( 4)^2 + 10 = 16 + 10 = 26$.
Common Questions
How do you evaluate a function?
Substitute the given input value for the variable in the function rule and simplify. For f(x) = 2x^2 - 3, f(4) = 2(16) - 3 = 29.
What does f(a) mean?
f(a) means the output of the function f when the input is a. You replace every occurrence of x with a in the function formula.
Can you evaluate a function for a negative input?
Yes. Just substitute the negative value carefully and follow order of operations. For f(x) = x^2, f(-3) = (-3)^2 = 9.
How do you evaluate a function from a graph?
Locate the input value on the x-axis, trace vertically to the graph, and read the corresponding y-value.