Question

Find the equation of the line

passing through the points 1,-5)
and (9,11).
y = 2x + [?]

Answer 1

y = 2x - 7

Explanation:

Looks like we already have the slope of this line: It is 2. Working with the point (1, -5), we have x = 1 and y = -5 and can from this info easily find the y-intercept, b:

y = mx + b becomes

y = 2x + b, which in turn becomes

-5 = 2(1) + b, or

b = -7,

and so the desired equation is y = 2x - 7