If the graph of the line y = ax + b passes through the points (4,5) and (8,17), what is a - b?
+36916 First, find the slope = rise/run = (y1-y2)/(x1-x2) = (5-17)/ (4-8) = (-12)/-4 = 3
This is 'a'
So the line , so far looks like
y = 3 x + b Now, let's put one of those x, y points in there to find 'b'
5 = 3(4) + b
5-12 = b b = -7
So the equation for this line is y = 3x -7 and a-b = 3-(-7) = 3 + 7 = 10
