Let line L_1 be the graph of 5x + 8y = -9. Line L_2 is perpendicular to line L_1 and passes through the point (10,-10). If line L_2 is the graph of the equation y=mx +b, then find m+b.
+128475 We first need to find the slope of L1
5x + 8y = -9
8y = -5x - 9
y = ( -5/8)x - 9/8
The slope = -5/8
L2 will have a negative reciprocal slope = 8/5
Since L2 passes through (10, -10) we have
y = (8/5) ( x - 10) - 10
y = (8/5)x - 16 - 10
y = (8/5)x - 26
m + b = 8/5 - 26 = -122/5
