Question

The equation of a line is y= -1/2x - 2. What is the equation of the line that is perpendicular to the first line and passes through the point (2, –2)?

Answer 1

If two line are perpendicular. The multiply of their slopes are equal to -1. 
First line's slope is: -1/2x because if the line equation is form of y=ax+b a is slope. 
Let say second line's slope is m
m.-1/2=-1  so m=2 
y=ax+b is general form of linear function/equation. (a=slope)
y=2x+b 
If this line passes through the point (2,-2),if we write -2 to y and 2 to x, the equation becomes true. 
-2=4+b
b=-6 
Thus, 
y=2x-6 is true answer.