**Odd and even functions:**
Function is even if it can be reflected across $y$-axis $\implies f(x)=f(-x)$
-If $n$ is odd, then $f$ is an odd function since $f(-x)=-f(x) \implies f(x)=-f(x)$
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+If $n$ is odd, then $f$ is an odd function since $f(-x)=-f(x) \implies f(x)=-f(x)$
+
+## Combinations of functions (piecewise/hybrid)
+
+$$\text{e.g.}\quad f(x)=\begin{cases} ^3 \sqrt{x}, \hspace{2em} x \le 0 \\ 2, \hspace{3.4em} 0 < x < 2 \\ x, \hspace{3.4em} x \ge 2 \end{cases}$$
+
+Open circle - point included
+Closed circle - point not included
+
+### Sum, difference, product of functions
+| | | |
+|---|-----|-----|
+|sum|$f+g$|domain $= \text{dom}(f) \cap \text{dom}(g)$|
+|difference|$f-g$ or $g-f$|domain $=\text{dom}(f) \cap \text{dom}(g)$|
+|product|$f \times g$|domain $=\text{dom}(f) \cap \text{dom}(g)$|
+
+Addition of linear piecewise graphs - add $y$-values at key points
+
+Product functions:
+- product will equal 0 if one of the functions is equal to 0
+- turning point on one function does not equate to turning point on product
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