## College Algebra 7th Edition

$y=7$
RECALL: (1) The slope-intercept form of a line's equation is $y=mx+b$ where m = slope and b = y-intercept. (2) The slope of a line can be found using the formula $m=\dfrac{y_2-y_1}{x_2-x_1}$ where $(x_1, y_1)$ and $(x_2, y_2)$ are points on the line. (3) The slope of a horizontal line is $0$ and its equation is of the form $y=k$ where $k$ is the y-coordinate of any point on the line. (4) The slope of a vertical line is undefined and its equation is of the form $x=h$ where $h$ is the x-coordinate of any point on the line. Solve for the slope to obtain: $m=\dfrac{7-7}{4-1} \\m=\dfrac{0}{3} \\m=0$ The slope is zero therefore the line is horizontal. The y-coordinate of the point is $7$. Thus, the equation of the line is $y=7$.