Answer
(a). $-5$,
(b). $y=-5x$
Work Step by Step
(a). From $x_1=0$ to $x_2=3$, we have the average rate of change as $\frac{h(x_2)-h(x_1)}{x_2-x_1}=\frac{(-2(3)^2+(3))-(-2(0)^2+(0))}{3-0}=-5$,
(b). The slope of the secant line is the same as the average rate of change in (a), $m=-5$, use one point $(0,0)$, we can find the equation as $y=-5x$
