If f(x) = x² − 4, f(3) = ?

**The reasoning** This is **function evaluation** — you're simply substituting the given value into the function. Given: f(x) = x² − 4, and you need f(3). Replace every "x" with "3": f(3) = (3)² − 4 f(3) = 9 − 4 f(3) = **5** Think of f(x) as a machine: you feed in x = 3, and it squares it, then subtracts 4. --- **Why the wrong options tempt you** **A) 1** — You might have done 3 − 4 + something confused. Wrong order of operations. **C) 9** — You stopped after squaring! You forgot to subtract the 4. This is the most common trap. **D) 13** — You probably added instead: 9 + 4. Sign error — the function says *minus* 4. --- **Quick takeaway** When you see f(3), **substitute 3 everywhere you see x**, then follow BODMAS carefully — square first, subtract last. Function evaluation is just careful substitution!