Question

Determine whether the following equation defines y as a function of x.

Answer 1

Answer:

The equation can define y as a function of x and it also can define x as a function of y.

Step-by-step explanation:

A relation is a function if and only if each value in the domain is mapped into only one value in the range.

So, if we have:

f(x₀) = A

and, for the same input x₀:

f(x₀) = B

Then this is not a function, because it is mapping the element x₀ into two different outputs.

Now we want to see it:

x + y = 27

defines y as a function of x.

if we isolate y, we get:

y = f(x) = 27 - x

Now, this is a linear equation, so for each value of x we will find an unique correspondent value of y, so yes, this is a function.

Now we also want to check if:

x +  y = 27

defines x as a function of y.

So now we need to isolate x to get:

x = f(y) = 27 - y

Again, this is a linear equation, there are no values of y such that f(y) has two different values. Then this is a function.