Question

What is the equation of the line that passes through the point (2, 3) and is perpendicular to the line y = –x – 3?

Answer 1

Since it is perpendicular to line y=-x-3, its slope must be 1.
(ab=-1 for two lines with slope a and b to be perpendicular)

So, the equation would be y=x+a (a is a constant)
Now plug in (2,3)
3=2+a a=1
y=x+1

Answer 2

perpendicular to the line y=-x-3
means the gradient of the perpendicular line is the negative reciprocal of y=-x-3

so the gradient = -1/-1=1