Is ab 0? (1) abc

Question

Is ab > 0 ? (1) abc < 0 (2) b^2c < 0 Source : https://www.GMATinsight.com

chetan2u · Answer

Is ab > 0 ? 1) abc < 0........(ab)*c<0 Thus, ab and c have opposite sign. If c>0, then ab<0. But if c<0, then ab>0. 2) b^2c < 0 b^2>0 , as b is not zero. Thus c<0. Nothing about ab. Combined c<0, so ab>0 C

hmayank83 · Answer

1) abc<0 => ab>0 and c<0 or ab<0 and c>0 Hence not sufficient . Eliminate A,E
2)(b^2)c>0 can be written as c>0 as b^2 will always be greater than 0. Not sufficient Eliminate B
Combining 1 and 2 we get ab<0 and c>0 which means abc<0
Hence we can arrive at a conclusion by combining the two statements.
C is the correct answer.

Archit3110 · Answer

target is ab>0? #1 abc < 0 possible when either all three are -ve or either of one is -ve case 1; if all three are -ve then ab>0 sufficient case 2: if either of one is -ve then yes / no insufficient #2 b^2c < 0 possible when c -ve b sign can be +ve or -ve but a is not known insufficient from1&2 we know c is -ve so as per case 2: a &b are of same sign therefore a*b>0 sufficient option C

KSBGC · Answer

we are to find out whether ab>0 or not . Statement 1: abc<0 this statement gives us 2 0ptions. 1. any of the a,b,c could be negative with other 2 positive. 2. all of them could be negative. thus , specifically we are not certain whether ab<0. statement 2: b^2 c <0 it indicates that c must be negative. since b has even power , it is not certain to assume that b is positive . ( 1 + 2) : Both statements together are sufficient. stat 2 proves that c<0 . as a result , both a and b have to be negative or both need to be positive . that will ultimately provide us ab>0 . a>0, b>0 ........ab> 0 or a<0 b<0 ab>0 Thus C is the correct answer.

Is ab > 0? (1) abc < 0 (2) b^2c < 0

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