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.
+128406 In the form Ax + By = C
The slope = -A / B
So....the slope of the first line is -5/8
The slope of L2 is the negative reciprocal of this = 8/5
The equation of L2 is
y = (8/5) ( x - 10) + 10
y = (8/5)x - 16 + 10
y = (8/5)x - 6
m + b =
(8/5) - 6 =
8/5 - 30/5 =
-22/5
See the graph here : https://www.desmos.com/calculator/4qx32mvehe
