## Intermediate Algebra (12th Edition)

(a) $y=7$ (b) $y=7$
(a) The line $x=9$ is horizontal (because it has the form $x=constant$) and thus a perpendicular line would be vertical (with the form $y=constant$). Since the line must pass through the point $(-2,7)$, we know that the form of the equation must be: $y=7$ (b) $y=7$ is in standard form.