Question 9342
f(x) = 2x - 1


First, this is a special notation that does NOT mean f times x.  It is a special notation that is read "f of x", and it means that you are to substitute a value of x into this formula and simplify the result to find the value of the answer.  It is MUCH easier than everyone can possibly imagine.

Given 
f(x) = 2x - 1  
f(-3) means that you sustitute the value of -3 in place of the x value(s).
f(-3) = 2(-3) - 1
f(-3) = -6 -1 = -7


You didn't ask for it, but if you need another example, suppose you wanted to find f(9) or f(-7).

f(9) = 2(9) - 1 = 18-1 = 17


f(-7) = 2(-7) - 1 = -14 -1 = -15


R^2 at SCC