Question

Question #1ed65

Answer 1

`f(x)=-0.1x-10`

Explanation:

For Company Y:

let `c_1=` the cost of making a phone call with Company Y's plan.

`color(red)(c_1=10+0.1x)`

For Company Z:

let `c_2=` the cost of making a phone call with Company Z's plan.

`color(blue)(c_2=0.2x)`

For the difference between the two companies:

It could go both ways:

`color(blue)(c_2)-color(red)(c_1)=0.2x-(10+0.1x)=0.2x-10-0.1x=color(green)(0.1x-10)`

`color(red)(c_1)-color(blue)(c_2)=(10+0.1x)-0.2x=10+0.1x-0.2x=10-0.1x=-color(green)(0.1x-10)`

As you can see, both paths lead to the same answer.

If there were a function `f(x)` that represents the difference in cost between Company Y and Company Z, then

`f(x)=-0.1x-10`

Hope this helped!