Current Student
Joined: 24 Dec 2018
Posts: 107
Concentration: Entrepreneurship, Finance
Re: What is the value of x? (1) (-x)^3 = -x^3 (2) (-x)^2 = -x^2
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29 Dec 2018, 11:59
I think the trap in this question lies in tricking you to think that statement 2 will also give a similar solution as statement 1 did. This tends to happen in a lot of DS questions with seemingly similar statements.
Lets dive in!
Statement 1: \((-x)^3 = -x^3\)
An odd power does not change the sign of a number.
So, whether x is positive or negative or 0, \((-x)^3\) will always be equal to \(-x^3\). To illustrate this point, lets take examples:
Case 1: x is 1
\((-1)^3 = -1^3\) which is essentially -1
Case 2: x is 0
\((-0)^3 = -0^3\) which is essentially 0
Case 3: x is -1
\((--1)^3 = --1^3\) which is essentially 1
Since we get no unique value for x, this statement is insufficient
Statement 2: Even power of a number always changes the sign of a number to non-negative.
Thus, \((-x)^2\) will be equal to \(x^2\)
Thus, expression translates to: \(x^2 = -x^2\)
Which implies: \(2x^2 = 0\)
Which implies x=0.
Hence, statement 2 is sufficient and answer is B