If f(x) = 5x – 1 find following f(a-2)

f(x) = 5x - 1

Make the x's red

f(x) = 5x - 1

Make the x's green

f(x) = 5x - 1

Make the x's p's

f(p) = 5p - 1

Make the x's scissors

f(") = 5" - 1  

Make the x's old timey telephones

f(() = 5( - 1

Make the x's smiley faces

f(J) = 5J - 1

Make the x's frowny faces

f(L) = 5L - 1

Make the x's airplanes

f(Q) = 5Q - 1

Make the x's two things, like this

f(@&) - 5(@&) - 1

Make the x's two other things

f(ON) = 5(ON) - 1

Make the x's three things

f(RmG) = 5(RmG) - 1

Make the x's these three things

f(a-2) = 5(a-2) - 1

All the algebra is on the right side. The left 
side is nothing but functional notation. So multiply
out the parentheses on the right side using the 
distributive law

f(a-2) = 5a - 10 - 1

Now we combine the -10 and the -1 and get -11

f(a-2) = 5a - 11

That is the answer. Do not do anything to the left 
side because that is not algebra to be done but only a 
notation, a symbol for what is on the right. Do you
see that all you do is substitute a-2 for x in the
parentheses on the left, then substitute (a-2) for x
on the right, and then we simplify?

Edwin