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Evaluating Functions

HSF-IF.A.2
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Aligned To Common Core Standard:

High School Interpreting Functions - HSF-IF.A.2

How to Evaluate Math Functions? Do you find it tiring when you have to explain a lot? Isn’t it always better to give a lot of information in the most precise way? Yes, it is. And this is at least possible in mathematics when you have to give too much complex information in fewer words. A function is a short and precise way of sharing information about the function without having to write long sentences. The most popular and shortest function notation is f (x) which is commonly read out as 'f of x', saying the function of x. It is important to notice here that it doesn't refer to multiplication or is not a sign of multiplication. The f (x) notation is just a different representation of the y-value in any given function, y = f (x). This y-axis could be denoted as f(x) when you are plotting it on a graph, and instead of writing it as (x, y) the ordered pairs could be written as (x, f (x)). To evaluate a function, you simply have to replace/substitute the value of x with the given number. For example, if yiu have a function with x, replace x with the number or expression. We know how to solve expressions. And guess what! Evaluating functions work very much like evaluating expressions. However, the difference comes in where the functions have "equals" sign like equations and formulas. Evaluating functions is actually replacing or substituting the variable in the function with a given number or expression. Let's take an example: Q. Evaluate the function: f(x) = 3x + 2 for x = 2 To solve, we replace the value of x with the number 2; f(2)= 3(2)+2 = 6+2 = 8 So, the answer is: f(2) = 8. This is an outstanding series of worksheets and lessons that teach students how to value and evaluate functions.

Printable Worksheets And Lessons


  • Finding f(x) Step-by-step Lesson- It's time to get acquainted with the function rule. In this case we show you to substitute values.

  • Guided Lesson - These are relatively simple functions to work with. You will need to find the missing values.

  • Guided Lesson Explanation - It comes down to properly plugging in numbers and then your basic order of operations from there.

  • Practice Worksheet - This one is all about evaluating the order in which integers are placed. Make sure to complete the problem simplifying your final answer.

  • Matching Worksheet - Match the functions to their outcomes. Also note that some will be equations.




Homework Sheets

Work with function rules to find the final value of f (x).

  • Homework 1 - Plug those values into the function and simplify. You are provided with a well thought out example.
  • Homework 2 - You will solve a rule based problem by plugging r + 3 into f (n) and then we simplify.
  • Homework 3 - In this case we are working with an exponent that we need to pay attention to.



Practice Worksheets

These problems are a bit more challenging than what you saw in the homework.

  • Practice 1 - Use the following function rule to find f (r + 2). You will run this into the end.
  • Practice 2 - You will finish these up by following through the entire problem.
  • Practice 3 - Take your time and take note of where you place those variables and how they fit into the equations.



Math Skill Quizzes

It's all about checking through given function rules.

  • Quiz 1 - What gets stuck in there is the things that you need to finish up with.
  • Quiz 2 - What is the value of f (x)? In some cases it will be given to you. In other cases you will need to rearrange the equation.
  • Quiz 3 - Where we put everything to rest. See how well you understood this topic.