Passes through (7, 6) and (10, 15)
y=mx+b
y is dependant, m is slope, x is independant, b is vertical shift
The equation for finding a slope is (Y1-y2)/(X1-X2).
(15-6)/(10-7)=9/3=3 so the slope is 3
y=3x+b
To find b, substitute an instance of y and x, for y and x. You can use 15 and 10 or 6 and 7, both give the same answer
15 and 10:
15=3(10)+b
15=30+b
-15=b
6 and 7
6=3(7)+b
6=21+b
-15=b
see?
so b=-15, and the formula is
y=3x-15.
The graph looks like
Note that the line crosses the vertical (y) axis at -15, b.
