Let line L1 be the graph of 5x + 8y= -9. Line L2 is perpendicular to line L1 and passes through the point (10, 10). If line L2 is the graph of the equation y = mx + b, then find m + b.

Logic Aug 25, 2018

#1**+3 **

5x + 8y = -9

In the form ax + by = c, the slope of this line is -a/b = -5/8

So...a perpendicular line will have a negative reciprocal slope = - (-8/5) = 8/5

So......the equation of a line with a slope of 8/5 passing through (10,10) is

y =(8/5)(x - 10) + 10

y =(8/5)x - 16 + 10

y = (8/5)x - 6

So.....m = 8/5 and b = -6 = -30/5

So....m + b = 8/5 - 30/5 = -22/5

CPhill Aug 25, 2018