
Max S. answered 02/11/20
Math and Physics Tutor with a Passion for Teaching
In point-slope form we write equations in the form:
y - y1 = m(x - x1)
where m is the slope of the line, and (x1,y1) is the point we're given.
We know that our equation should be parallel to y = 9x, so our equation should have the same slope as this one. Therefore, m = 9.
Plugging in our given point, (0,-5), and the slope we found we get:
y - y1 = m(x - x1)
y - (-5) = (9)(x - 0)
y + 5 = 9x