Question

What is the slope and equation of a line parallel to the y-axis passing through point (9, -1)?

Answer 1

Answer:

The slope is undefined and the equation of the line is x = 9 ⇒ C

Step-by-step explanation:

• Parallel lines have the same slopes and different y-intercepts

• The slope of any vertical line is undefined

• The equation of any vertical line is x = a, where a is the x-coordinate of a point that lies on the line

• All x-coordinates of the points lie on a vertical line equal

Let us solve the question

∵ The line is parallel to the y-axis

∵ The y-axis is a vertical line

→ By using the second note above

∴ The slope of the y-axis is undefined

→ By using the first note above

∴ The slope of the line is undefined

→ By using the third note above

∵ The equation of the vertical line is x = a

∵ a is the x-coordinate of a point on the line

∵ The line passes through the point (9, -1)

∴ a = 9

∴ The equation of the line is x = 9