Answer
slope = $\dfrac{-b}{a}$
The line that passes through the two given points falls from left to right.
Work Step by Step
RECALL:
(i) The slope, $m$, of the line that passes through the points $(x_1, y_1)$ and $(x_2, y_2)$ is given by the formula:
$m=\dfrac{y_2-y_1}{x_2-x_1}$
(ii) A line whose slope is positive rises from left to right.
(iii) A line whose slope is negative falls from left to right.
(iv) A horizontal line has a slope of zero.
(v) A vertical line has an undefined slope.
Use the formula in (i) above to find the slope of the line that passes through the points $(-a, 0)$ and $(0, -b)$ to obtain:
$m=\dfrac{-b-0}{0-(-a)}=\dfrac{-b}{0+a}=\dfrac{-b}{a}$
$\dfrac{-b}{a}$ is negative.
Thus, the line that passes through the two given points falls from left to right.
