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

(a) $-9$ (b) $\frac{1}{9}$
RECALL: (i) The slope-intercept form of a line's equation is $y=mx+b$, where m=the slope and b=the y-intercept. (ii) Parallel lines have equal slopes. (iii) Perpendicular lines have opposite reciprocal slopes. The given line has $m=-9$, so its slope is $-9$. Thus, (a) The slope of any line parallel to the given line is: =$-9$ (b) The slope of any line perpendicular to the given line is: $=\frac{1}{9}$