## Thomas' Calculus 13th Edition

$a.\quad x=-1$ $b.\displaystyle \quad y=\frac{4}{3}$
$a.\quad$ Vertical lines contain points $(x,y)$ that all have the same x-coordinate. Given that $(-1, \displaystyle \frac{4}{3})$ lies on the line and has its x-coordinate equal to $-1$, the vertical line has the equation $x=-1$ $b.\quad$ Horizontal lines contain points $(x,y)$ that all have the same y-coordinate. Given that $(-1, \displaystyle \frac{4}{3})$ lies on the line and has its y-coordinate equal to $\displaystyle \frac{4}{3}$, the horizontal line has the equation $y=\displaystyle \frac{4}{3}$