Is x = 1?

1. \(x^4\)=1
This means x=1 or x=-1
Not Sufficient

2.\(x^3\)=1
x=1
Sufficient

Option B

Hello,

Statement 1 : x^2=1/x^2 => x^4=1. X can take both values -1 and 1. Hence not sufficient.
Statement 2 : x^2=1/x => x^3 = 1. Odd power preserves the sign hence x can only be 1. Sufficient.

Statement B gives us a definite value of x i.e. 1. Hence Answer B

MANHATTAN GMAT OFFICIAL SOLUTION:

If you are doing this wrong, you would assume a “Yes” for the question, then plug into the statements. For instance, you would plug x = 1 into each statement. You would see that the value fits the equations in both statements, and you would pick D incorrectly. That's especially easy to do in this case, because this particular question is much simpler to think about than the statements (which are nasty little equations).

Don't do this wrong! No matter what, when you are judging sufficiency, you should always proceed from the facts to the question. It doesn't matter how easy or hard the question is at that point. After you've rephrased, put the question on hold and work from the statements and any other given facts to the question:


The correct answer is B.

!

In a Yes/No question, when evaluating the statements, always try to determine whether the question can be answered the same way under any possibility that is consistent with those facts. Simply checking to see whether the question might be true given the facts from the statements is sloppy, and will often lead to an incorrect answer.