# Thread: Finding a linear equation which passes through points

1. ## Finding a linear equation which passes through points

Ok, Im not quite sure what to do here, could anyone help please?

i have 4 questions

1) (7,0) (0,2)

2) (2,4) (-3,1)

3) (-3,2) (6,8)

4) (4,3) (8, 12)

help would be much appreciated

thank you all

2. Originally Posted by damonneedshelp
Ok, Im not quite sure what to do here, could anyone help please?

i have 4 questions

1) (7,0) (0,2)

2) (2,4) (-3,1)

3) (-3,2) (6,8)

4) (4,3) (8, 12)

help would be much appreciated

thank you all
I will do 2) for you, the rest are done by an identical method.

The two points are (2, 4) and (-3, 1). The slope of the line between these points is, by definition:
m = (y2 - y1)/(x2 - x1) where (x1, y1) and (x2, y2) are your two points.

So
m = (1 - 4)/(-3 - 2) <-- You can put the points into this equation in either order.

m = -3/(-5) = 3/5.

Now the form of the line will be
y = mx + b

y = (3/5)x + b

Now we put one of the two points into this formula to find a value for the y intercept coordinate b. Either point may be used. I'll use (2, 4).

4 = (3/5)*2 + b

4 = 6/5 + b

b = 4 - 6/5 = 20/5 - 6/5 = 14/5

y = (3/5)x + 14/5

Just to check, let's put in the other point, (-3, 1).
y = (3/5)x + 14/5

1 = (3/5)*(-3) + 14/5

1 = -9/5 + 14/5 = 5/5

1 = 1 (Check!)

-Dan