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If k^2 = m^2, which of the following must be true? [#permalink]
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14 Oct 2015, 21:24
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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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14 Oct 2015, 21:28
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k = m suffice the condition of k^2 = m^2.
so ans: E

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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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14 Oct 2015, 22:21
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k^2=m^2 Taking the non negative square root of both sides of the equation , k = m Answer E
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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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14 Oct 2015, 22:35
Bunuel wrote: If k^2 = m^2, which of the following must be true?
(A) k = m (B) k = −m (C) k = m (D) k = −m (E) k = m
Kudos for a correct solution. With Even powers of variables the signs can't be predicted about them Hence, We can't say anything about the sign of k and m being positive or negative therefore, Option A, B, C and D are ruled out as all these options are hinting towards specific and known sign of k and/or m For any sign of k and m, their absolute values must be same because k^2 = m^2, therefore, k = m Answer: Option E
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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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15 Oct 2015, 00:11
Forget conventional ways of solving math questions. In PS, IVY approach is the easiest and quickest way to find the answer. If k^2 = m^2, which of the following must be true? (A) k = m (B) k = −m (C) k = m (D) k = −m (E) k = m Since k^2=m^2 we have 0=k^2 – m^2 =(km)*(k+m). So k=m or k=m. So only (A) and only (B) cannot be an answer. The choice (C) tells us that k should be greater than or equal to 0. Similarly the choice (D) tells us that k should be less than or equal to 0. So neither (C) nor (D) cannot be the answer. The answer is, therefore, (E).
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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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24 Oct 2015, 02:18
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Bunuel wrote: If k^2 = m^2, which of the following must be true?
(A) k = m (B) k = −m (C) k = m (D) k = −m (E) k = m
Kudos for a correct solution. As squaring hides the sign of a number, k^2 will equal m^2 for every possible positive/negative combination of the two values. The only statement we can make for sure is therefore (E) k = m.

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Re: If k^2 = m^2, which of the following must be true? [#permalink]
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