f′(x) = slope of f(x)

Meaning: $f^{'} (x)$

The 1 ^st Derivative tells you about the slope of the original function, $f (x)$ .

$f^{'} (x) = positive (+) = positive slope = increasing$

$f^{'} (x) = negative (-) = negative slope = decreasing$

$f^{'} (x) = zero (0) = zero slope = not increasing or decreasing = critical value$

Reading the 1 ^st Derivative off another graph.

Reading the graph of a 1 ^st Derivative.

The y-values of the derivative graph correspond to the slope of the original function, $f (x)$ .

y-value = slope