The complete graph of y = f(x) , which consists of five line segments, is shown in red below. (On this graph, the distance between grid lines is 1 .)
What is the sum of the x-coordinates of all points where f(x) = 1.8?
+128474 Only two places where f(x) = y =1.8
Leftmost lsegment contains the points ( -3,0) and (-5, 4)
Slope = [ 4 - 0] / [ -5 - -3] = 4 / -2 = -2
Equation of the line containing this segment
y = -2 ( x +3)
1.8 = -2 (x + 3)
-9/10 = x + 3
-9/10 - 3 = x
-9/10 - 30/10 = x
(-39/10) = x = -3.9 because of symmetry, x = 3.9 is another solution
The sum of the x coordinates = 0
