# Video: Writing the Rule of an Input-Output Table as an Equation

In this function machine, we put π₯ in and get π¦ out. Which of these equations describes the rule? [A] π¦ = π₯ + 5 [B] π¦ = π₯ + 8 [C] π¦ = π₯ Γ 5 [D] π¦ = π₯ Γ 8 [E] π¦ = π₯ β 5.

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### Video Transcript

In this function machine, we put π₯ in and get π¦ out. Which of these equations describes the rule? π¦ equals π₯ plus five, π¦ equals π₯ plus eight, π¦ equals π₯ times five, π¦ equals π₯ times eight, or π¦ equals π₯ minus five.

This function table has given us a very important clue. In this function machine or in this function table, you multiply π₯ by five and that gives you π¦. For example, if we have an π₯-value of two, we multiply two times five and that gives us our π¦-value of 10.

We are looking for an equation that says π¦ equals π₯ times five. Only one of the answer choices β only one of the equations β describes the rule correctly π¦ equals π₯ times five.