Step-by-step explanation:
When the slope of the function is positive, it is increasing
when the slope of the function is negative, it is decreasing
just like with the line function y = mx + b
so if you put a line tangent to the function at every point the slope of the line will indicate a increasing or decreasing point of the function
also beware where the slope is zero it is not increasing or decreasing
there are two intervals of increasing, one interval of decreasing and two point of zero slope or neither increasing or decreasing
increasing interval 1) x < -2 2) x > 1.5
decreasing interval 1) -2 < x < 1.5
at -2 and 1.5 the slope is zero
