Question 634990
{{{f(x)=x^2-1}}}
This tells us that the function named "f" takes whatever input you give it (here represented by "x") and squares it and then subtracts 1. This function f will square <i>any</i> input and then subtract 1.<br>
f(a) is what you get from f when you give it an input of "a". And what does f do to its input? Answer: It squares it and then subtracts 1. So:
{{{f(a) = a^2-1}}}<br>
For f(a)-3 we just take f(a) and then subtract 3:
{{{f(a) - 3 = (a^2-1) - 3 =  a^2 - 4}}}