Question

Write equations for the horizontal and vertical lines passing through the point (3,9)

Horizontal line:
Vertical line:

Answer 1

Horizontal: y = 9

Vertical: x = 3

Explanation:

Any point is given in the form (x,y). The first number is the x and the second number is the y.

Horizontal lines (a left-right line like the horizon) have an equation in the form "y = anumber" This works because a horizontal line has ZERO slope. So there is no x in the equation because--

y = 0x + b

y = b (a number, use the y-number from the point)

A vertical line has undefined slope so you can't even pretend to use a slope equation. A vertical line (up and down) has an equation in the form

"x = anumber" Use the x from the point.

Horizontal line through (3,9) is y=9.

Vertical line through (3,9) is x=3