The slope is three times the y-intercept and through (-3,10). How do I know the equation?

Answer 1

Let the y-intercept be (0,k). Now you have two points, so the slope is
(10-k)/-3
We are told that the slope is 3k, so that makes m = k-10
The point-slope form for the line is now
y-10 = (k-10)(x+3)

Answer 2

P(-3, 10).
Y = mx + b,
m = 3b,
Y = (3b)x + b,
10 = (3b)(-3) + b,
b = -10/8 = - 5/4 = -1.25.
m = 3b = 3*(-1.25) = -3.75.
Eq: Y = -3.75x - 1.25.

Answer 3

well, duh.
Nice save, henry2

Answer 4

Thanks, oobleck.