a. The domain is the x values so to find the domain used to graph

\(f(x)=2x−4\),

you need to determine what values this piece is defined for. From the piece-wise defined function,

\(f(x)=2x−4\)

is defined for −1 b.

If you are finding f(4), then \(x=4\).

From the piece-wise defined function, the domain that includes \(x=4\)

is \(2\leq x<\).

This domain is for the piece of \(f(x)=3x\).

Therefore, the equation \(f(x)=3x\) is used to find \(f(4)=12\).