# Which of these equations represent functions where x is the input and y is the output?

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Select each answer that applies

A. X=2

B. Y=2

C. Y=2x

D. X=2y

E. X+y=2

Select each answer that applies

A. X=2

B. Y=2

C. Y=2x

D. X=2y

E. X+y=2

##### 1 Answer

#### Answer

#### Answer:

#### Explanation

#### Explanation:

#### Answer:

**C. is the answer.**

#### Explanation:

**Question:**

Which of these equations represent functions where **x** is the **input** and

**y** is the **output** ?

List:

A.

B.

C.

D.

E.

- For this problem we can ignore the fact that some of the variables are Capital letters and others small letters.

In such problems, it is helpful to look at each piece and evaluate it to see if it fits the requirements.

**First look at the list:**

Look for equations that involve both x and y, since they are both required.

**Selections A. and B. are eliminated,** since they only involve one of the variables.

**Thinking about what input and output mean:**

You "Input" something, do something to it and produce an output. Kind of like putting water into the 'frig, and getting ice as the output.

Which ones in the list involve putting an x in, doing something to it and getting a y value as a result?

Look at each of the others in the list:

**For C.**

You can **put in an x value, do something to it** and **get a y out**.

So, **C. is one of the possible answers.**

**For D.**

It seems you must do something to a y-value to get an x value.

So, **D. doesn't qualify** as a solution.

**In E.**

It looks as though **you need to put in both an x and a y value, do something to them** (add them) **to get a number, 2.**

**E. doesn't qualify, either.**

Conclusion:

**C. is the answer.**

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