Question

Find the equation of the line which passes through the points (0,3), (-1, –4) in the point–slope form

Answer 1

Find the slope.

(y2 - y1)/(x2 - x1)
= (-1-0)/(-4-3)
= -1/-7
= 1/7

Point slope is:

(y-y1) = m(x-x1)

Pick one set of coordinates to plug in for x1 and y1, m is slope, as above.

Using (0-3):

y - (-3) = (1/7)(x - 0)
y + 3 = (1/7)x

Subtract 3 from both sides.

y + 3 - 3 = (1/7)x - 3
y = (1/7)x - 3

Answer 2

thanks so much! but why is -1/-7 not just -1/-7 instead of 1/7?

Answer 3

I used (0, -3) instead of (0,3) so just make the substitution.

-1/-7 is a negative divided by a negative, so you get a positive.