## Precalculus (10th Edition)

a) $-\dfrac{1}{2}$ b) If $x$ decreases by $2$ units, then $y$ increases by $1$ unit.
We know that by the Slope Formula: if $P_1(x_1,y_1)$ and $P_2(x_2,y_2)$ are on a line, then the slope is: $m=\dfrac{y_2-y_1}{x_2-x_1}$. a) Solve for the slope using the formula above to obtain $m=\dfrac{1-0}{-2-0}=-\dfrac{1}{2}$. b) A slope of $-\dfrac{1}{2}$ means that if $x$ decreases by $2$ units, then $y$ increases by $1$ unit.