If a^6 - b^6 = 0, what is the value of a^3 - b^3? (1) b is

Question

If a^6 - b^6 = 0, what is the value of a^3 - b^3?

(1) b is greater than 1
(2) a is positive

rxs0005 · Answer

sin e we have to find the value the answer to this is E

HowManyToGo · Answer

C.

using (1) and (2) we know that a^3 + b^3 is not zero. Hence a^3 - b^3 should be zero.

HMTG.

rxs0005 · Answer

u r right since both a and b are +ve the value of a^3 - b^3 will always be zero

ashkg · Answer

a^6 - b^6 = 0

implies (a^3+b^3)(a^3 - b^3) = 0

A &B are insufficient as knowing value of only 1 variable is not enough to show that (a^3+b^3) is +ve

C. both a,b >0
so 
(a^3+b^3) >0
so 
(a^3-b^3) must = 0

sifficient

tarungmat · Answer

My answer is C.

Statement 1: Insufficent. A and D options are ruled out.
Stetament 2: Insufficient. B is ruled out.

Combined together, we conclude that A and B are both are positive hence a^3 + b^3 can not be zero. This forces a^3 - b^3 to be zero. Hence C.

Note : a^6 - b^6= (a^3 + b^3 ) (a^3 - b^3 )

If a^6 - b^6 = 0, what is the value of a^3 - b^3? (1) b is

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