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If a + b = 2, a + c = 7, and b + c = 9, find a + b + c.

 Jul 1, 2020
 #1
avatar+712 
+1

a+b+c=9

 Jul 1, 2020
 #3
avatar+712 
0

there's 2 ways to solve this.

 

1. you can just experiment, and you can see that a=0, b=2, and c=7

 

2. we see that a+b+a+c=b+c

2a+b+c=b+c

2a=0

a=0

from there, you can find the other values :)

lokiisnotdead  Jul 1, 2020
 #2
avatar+637 
+1

a+b=2

a+c=7

b+c=9

 

Add all three equations together to get 2a+2b+2c=18. We divide this equation by 2 to get a+b+c=9.

 Jul 1, 2020
 #4
avatar+1013 
+1

2+7+9=a+b+a+c+b+c=2a=2b+2c so we then finally divide by 2 to get a+b+c=9

 Jul 1, 2020

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