Answer:
y = 9
Step-by-step explanation:
To find the equation of a horizontal line through a point, equate the y-coordinate of the point to y.
The y-coordinate is 9. Equate it to y.
y = 9
y
-------------|-A---------
<u> | </u> x
|
|
See the Cartesian plane that you graph in. The x-axis and y-axis meet at point (0, 0). Points, or ordered pairs, are written (x, y), which is how far you move left/right on the x-axis, then from there, how far up/down you go.
Horizontal lines go from left to right and are parallel to the x-axis.
The equation of the x-axis is y=0 because it meets the y-axis at 0.
(Pretend) the letter A marks the point (1,9). It moved right one unit, then up 9 units. The horizontal line would hit the y-axis at 9 (and not 0 like the x-axis). Therefore the equation for the horizontal line through (1, 9) is y = 9.
