+0  
 
+2
1160
3
avatar+885 

A line segment has one endpoint at (3,9) and midpoint at (1,2) . What is the sum of the coordinates of the other endpoint?

 Mar 23, 2017
 #1
avatar+129895 
+1

We have

 

( 3 + x) / 2  =  1          and              (9 + y ) / 2  =  2

 

Multiply both side by 2

 

3 + x   = 2                   and               9 + y   =  4

 

subtract 3 from both sides              subtract 9 from both sides

 

x  = -1                                              y  =  -5

 

This is the other endpoint

 

And the sum of its coordinates  =  -6

 

 

 

cool cool cool

 Mar 23, 2017
 #2
avatar+885 
+1

Thanks so much! Your're so smart!

ant101  Mar 23, 2017
 #3
avatar+2 
+1

The answer would be -6, you're right

 Mar 23, 2017
edited by algebrarocks  Mar 23, 2017

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