Question

What is the equation of a line that passes through the points (-3,6) and (1,2) ?

Answer 1

slope-intercept equation of a line: y = mx + b, where m is slope and b is y-intercept. Slope is change in y over change in x: (2 - 6) / (1 - -3) = -1. Then you plug that in for m in the above equation and use one of the points given and plug that in for x and y (I'll use the second point):

y = mx + b
2 = -1 + b
b = 3

So the equation is y = -x + 3
Here's the graph: http://bit.ly/qOTgsn

Answer 2

Why does b= 3 ?

Answer 3

I plugged "2" from the second point in for y, "1" for x, and "-1" for m. Then I solved for b:

y = mx + b
(2) = (-1)(1) + b
2 = -1 + b

Then add 1 to each side:

3 = b

Answer 4

Can I use first point of y or is it necessary that I use second y to solve this equation?

Answer 5

you can choose either point, because by definition they both satisfy the equation. I chose the second one because it looked easier.

Answer 6

Oh i get it now tysm :)

Answer 7

ymtw