Peter S. answered 07/07/20
Middle/High School Math Tutor and Guitar Teacher
Hey Isabela!
We want the perpendicular slope to the line y = 3x - 7. The slope of a line perpendicular to m=3 (the slope of the line in the given equation) is the negative reciprocal of m=3. So in this case we are looking for the slope
-1/m = -1/3
Then we put the point into "point slope form" and then solve for y to put it in slope intercept form.
y - (-6) = -1/3 * (x-4)
y+6 = -x/3 +4/3 distribute and simplify
y = -x/3 +4/3 -6 subtract 6 from both sides
y = -x/3 -14/3 combine constants ( 6 = 18/3 ). Solved
y = -x/3 -14/3 is the line perpendicular to y = 3x - 7 and goes through the point (4,-6)
I hope this helps
-Pete