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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 -coordinates of all points where f(x)=1.8?
 

 Dec 25, 2018
 #1
avatar+101870 
+2

The equation of the line joining  (0, 0) and (1, 2)  is

y = 2x

So  when y = 1.8   x =  .9

 

The equation of the line joining (1, 2) and (2, 1) is

y = -(x - 1) + 2

y = -x + 3

So.....when y = 1.8

1.8 = - x + 3

-1.2 = -x

1.2 = x

 

The equation of the line joining (2, 1) and (3, 3)  is

y = 2(x -3) + 3

y = 2x - 6 + 3

y = 2x - 3

When y = 1.8

1.8 = 2x - 3

4.8 = 2x

2.4 = x

 

I assume you want the sum of the x coordinates when y = 1.8???

 

If so...we have

 

.9 + 1.2 + 2.4   =

 

4.5

 

 

cool cool cool

 Dec 25, 2018
 #2
avatar+814 
+1

Thank you, CPHill!

mathtoo  Dec 25, 2018
 #3
avatar+101870 
0

Thanks, mathtoo......

 

cool cool cool

CPhill  Dec 25, 2018

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