### Home > CC4 > Chapter 1 > Lesson 1.1.1 > Problem 1-6

In what order must she put the machines to get a final output of

? Substitute

for in the first function.Let the output from the first equation become the input,

, in the second equation.

Incorrect. Try the other order.Substitute

for in the 2nd equation.

Let the output from the second equation become the input,

*x*, in the fist equation.

Correct!Is it possible for her to find an initial input that will get a final output of

? If so, show how she could do that. If not, explain why not.

Which equation cannot have a negative output? What input would you need from the other equation to get

as an output? See part (a) for more help.