## Intermediate Algebra for College Students (7th Edition)

slope = $\dfrac{-a}{b}$ The line through the points falls from left to right.
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 line 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 $(0, a)$ and $(b, 0)$ to obtain: $m=\dfrac{0-a}{b-0}=\dfrac{-a}{b}$ Since both $a$ and $b$ are positive, then $\dfrac{-a}{b}$ must be negative. Thus, the line that passes through the two given points falls from left to right.