Explanation:
Since it is asking for a perpendicular line, we take the reciprocal of the slope in the given equation to use as the slope for the perpendicular line.
In y = x + 2, m = 1. However, for a perpendicular line we flip and multiply by a negative 1.
(Example: If m = 3, we would take the reciprocal of it and it turns into m = -1/3. If m = - 1/4, we would take the reciprocal of it and it turns into m = 4.)
So, the m = 1 turns into a m = -1.
Now, you can use the point (4,-1) to form a point-slope equation first.
y-(-1) = -1(x-4)
Then, use basic algebra to form a slope-intercept form equation.
y + 1 = -x + 4
y = -x +3