(4,?) is on the line y = 2x 3
The line y = 2x 3 is in slope-intercept form
2 = slope
3 = y intercept
A line perpendicular to the line y = 2x 3 will have a slope of 1/2 which is the inverse reciprocal of 2
y = 1/2x + b
Use the point you want to go through to find 'b'
4 = 1/2(2) + b
4 = 1 + b
b = 5
y = 1/2x + 5
Answer = 2;(4,2) is on the line y = 2x 3
