Is A + B + C = 0? (1) A = -B (2) B = C

Question

Is A + B + C = 0?

(1) A = -B 
(2) B = C

M36-27

Archit3110 · Answer

from1 :
A=-B but no info of C
so -b+b+c=0
c=0 , 
not sufficient

from 2: B=C
A+B+C=0
A+2B=0
combining both wont get us any solution as well
IMO E

DavidTutorexamPAL · Answer

The answer is E.  
1) and 2) are obviously insufficient on their own, as each only gives info on two of the three variables. 
combining them and representing A and C n terms of B, we get A+B+C = -B+B+B = B. But we don't know if B equals zero or not! insufficient.

DavidTutorexamPAL · Answer

Archit3110  notice you are solving it as if the equation A + B + C = 0 is a given, but actually - the question is whether this equation is true or not.

Archit3110 · Answer

DavidTutorexamPAL  :
yeah understood , where i went wrong.. E would be correct in that case ..

anshkool4u · Answer

Answer should be E.
This is because 
1. A=-B
This will give A+B+C as -B+B+C which equals C.Since value of C is not known,we cannot say whether A+B+C equals 0.
Hence insufficient.

2 B=C, doesn't gives any further information on value of C.Hence insufficient.

Combining 1&2,we still can't find the value of C.
Hence insufficient.
So,answer will be E

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Salsanousi · Answer

From statement 1

- B + B + C = 0?

We have C = 0? We don’t know the value of c so it is insufficient.

Statement 2

B = C

A + 2B = 0? We have 2 variables and 1 equation so insufficient.

Combined statement 1 and 2

A = - B

- B + 2B = 0

We have B = 0? Not sufficient.

Answer choice E

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GMATINSECT · Answer

Hi , 
you got the answer correct however , you cannot assume -b+b+c = 0 
This question stem was whether a+b+c = 0 ? 
We cannot take a+b+c=0 ! This is no where given .

Bunuel · Answer

Par of  GMAT CLUB'S New Year's Quantitative Challenge Set

Bunuel · Answer

Official Solution:

Is  A + B + C = 0 ? 
 
(1)  A = -B 
 
The question becomes:  is  (-B) + B + C = 0 ? , and then  is  C = 0 ?  We don't know the answer to this question. Not sufficient.
 
(2)  B = C 
 
The question becomes:  is  A + C + C = 0 ? , and then  is  A + 2C = 0 ?  We don't know the answer to this question. Not sufficient.
 
(1)+(2) We know that  B = -A = C , so the question becomes:  is  (-B) + B + B = 0 ?  and then  is  B = 0 ?  We don't know the answer to this question. For example, if  B = -A = C=0 , then  A + B + C = 0  but if  B = -A = C=1 , then  A + B + C = 1 . Not sufficient.

Answer: E

Is A + B + C = 0? (1) A = -B (2) B = C

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