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Describe the Concept of a Function (or Formula)
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The first video in this lesson will go over the following vocabulary words:

• Expression = A statement using numbers and/or variables and an operator.
• Equation = Expressions with an equal sign (=).
• Formula = An equation that gives us instructions or a rule.
• Function = An equation where every input has only one output.
Expression, Equation, Formula, Function

The following video will explain more about how a function works using the metaphor or parable of a seed. Just as a seed is only able to produce the one plant it is meant to create, a function can only produce one output for each input value.

Understanding Functions

This video references the following talk by Elder Uchtdorf: God's Harvest.

### Practice Problems

1. Choose the answer that will correctly complete the following sentence. Each unique input into a function can lead to ____. (
Solution
Solution:
1. only one output
)
1. only one output
2. several outputs
3. a random number of outputs
2. Choose the answer below that is an expression. (
Solution
Solution: 3. $$3 − 1$$
Details:
There is only one expression listed. It is $$3 − 1$$. Equations have equal signs in them. Expressions do not. Expressions have numbers, variables, and operations but not an equal sign. (Some examples of operations are addition, subtraction, multiplication, etc.)
)
1. $$3x = 2$$
2. $$5 + 1 = x$$
3. $$3 − 1$$
3. Choose the answer below that is an equation. (
Solution
Solution: 3. $$5 + 1 = x − 2$$
Details:
There is only one equation listed. It is: $$5 + 1 = x − 2$$. We know it is an equation because it contains an equal sign.
)
1. $$3 + 4$$
2. $$2x$$
3. $$5 + 1 = x − 2$$

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