Functions in Math

vertical line test is if a vertical line passes through a graph at more than 1 point, then it's not a function; otherwise it's a function
domain: D, set of x values
- beware of Restrictions
range: R, set of y values
when simplifying the function, better not to keep the 2 negative
one-on-one function: a function such that for each value of y there's exactly one value of x, if $x_{1} \neq x_{2}, t h e n y_{1} \neq y_{2}$
horizontal line test: if a horizontal line passes through a graph at more than one point, then the function is not one-to-one function
$f (g (x))$ = f function of the g function
$f (x) g (x) = (f g) (x)$ .
$y = a x^{2} + b x + c$
- a, b, c called co-efficient
inverses (reflection over y=x)
fraction - numerator / denominator
$f^{- 1} (x)$ pronounced as ([Eff inverse of ecks]).
- $f (f^{- 1} (x)) = x$ .