Question

Ex. 1 Write an equation in slope-intercept form for the line that passes through (3, 8) and is

perpendicular to the line with equation y = -1/3x+8

Answer 1

Explanation:

The line perpendicual to a reference line will have a slope that is the negative inverse of the reference line. In this case, the reference line is y= -(1/3)X+8, with a slope of -(1/3). The negative inverse would be 3. So the new line would have the form:

y = 3x + b

To find b, the y-intercept, use the given point and solve for b:

y = 3x + b

or 8 = 3*3 + b for the point (3,8)

8=9+b

b= -1

Thje equation of the line perpendicualr to the reference line and going through point (3,8) is:

y = 3x - 1

See attached graph.