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

Kathryn Kingham

In this function machine, we put π‘₯ in and get 𝑦 out. Which of these equations describes the rule? [A] 𝑦 = π‘₯ + 5 [B] 𝑦 = π‘₯ + 8 [C] 𝑦 = π‘₯ Γ— 5 [D] 𝑦 = π‘₯ Γ— 8 [E] 𝑦 = π‘₯ βˆ’ 5.

01:25

Video Transcript

In this function machine, we put π‘₯ in and get 𝑦 out. Which of these equations describes the rule? 𝑦 equals π‘₯ plus five, 𝑦 equals π‘₯ plus eight, 𝑦 equals π‘₯ times five, 𝑦 equals π‘₯ times eight, or 𝑦 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 𝑦. For example, if we have an π‘₯-value of two, we multiply two times five and that gives us our 𝑦-value of 10.

We are looking for an equation that says 𝑦 equals π‘₯ times five. Only one of the answer choices β€” only one of the equations β€” describes the rule correctly 𝑦 equals π‘₯ times five.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.