Question

Select the equation of the line that passes through the point (2, 6) and is perpendicular to the line x = 4.

Answer 1

Perpendicular lines have opposite reciprocal slopes. 

x = 4 has a slope of undefined since it is a vertical line.

It's undefined because 1/0 = undefined. We can't divide by 0.

The opposite reciprical of 1/0 is -0/1, which equals to 0.

Any line with a slope of 0 is:

y = 0x + b
y = b

This line goes through the point of (2, 6).

Since the equation starts with y = something, we have to use the y-value of the point it goes through. The point is in the form of (x, y).

6 is in the y-value.

The equation of the perpendicular line is y = 6.