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What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a

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Bunuel
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What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   04 Mar 2022, 02:30
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What is the value of a^4 - b^4 ?

(1) a = 3
(2) b = a



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What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   Updated on: 04 Mar 2022, 04:46
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Bunuel wrote:
What is the value of a^4 - b^4 ?

(1) a = 3
(2) b = a



Project DS Butler Data Sufficiency (DS3)


For DS butler Questions Click Here


to find the value of a^4 - b^4, we need values of both a and b or the relationship between them

Statement 1: NOT SUFFICIENT

Statement 2: b=a

i.e. a^4 - b^4 = 0

SUFFICIENT

Answer: Option B

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Originally posted by GMATinsight on 04 Mar 2022, 03:02.
Last edited by GMATinsight on 04 Mar 2022, 04:46, edited 1 time in total.
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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   04 Mar 2022, 03:57
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(1) a=3 does not tell us anything about the value of b. Insufficient to determine the value of a⁴-b⁴

(2) b=a, though it does not tell us the magnitudes of a & b but the fact that they are equal is sufficient to cancel out their 4th powers, or any powers for that matter. a⁴-b⁴ = b⁴-b⁴ = 0. Sufficient.

Hence, B.

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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   04 Mar 2022, 04:45
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kungfury42 wrote:
GMATinsight wrote:
Bunuel wrote:
What is the value of a^4 - b^4 ?

(1) a = 3
(2) b = a



Project DS Butler Data Sufficiency (DS3)


For DS butler Questions Click Here


to find the value of a^4 - b^4, we need values of both a and b or the relationship between them

Statement 1: NOT SUFFICIENT

Statement 2: NOT SUFFICIENT

Combining, we have both a and b so SUFFICIENT

Answer: Option C

CLICK HERE For Accessing 250+ FREE Videos on Number properties and DS and SUBSCRIBE the channel


1st Video solutions based Modular On-Demand QUANT Course: All Concepts | 2000+Qns | 20+ Tests |
Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub :)


Hi GMATinsight,

I think the answer to this should be B and not C. Could you please check?

Statement 2 tells us that b=a, and even though it does not tell us the magnitudes of a & b but the fact that they are equal is sufficient to cancel out their 4th powers, or any powers for that matter.

a⁴-b⁴ = b⁴-b⁴ = 0. Sufficient.

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Yes you are right. I read it on phoen and read second statement as b = 2


Yes the answer is B and I am making changes in explanation accordingly. :)
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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   04 Mar 2022, 22:45
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find value of a^4-b^4
#1
a=3 ; value of b not known insufficine
#2
a=b
in that case value of a^4-b^4 would be '0'
sufficient
option B

Bunuel wrote:
What is the value of a^4 - b^4 ?

(1) a = 3
(2) b = a



Project DS Butler Data Sufficiency (DS3)


For DS butler Questions Click Here
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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   04 Mar 2022, 03:58
GMATinsight wrote:
Bunuel wrote:
What is the value of a^4 - b^4 ?

(1) a = 3
(2) b = a



Project DS Butler Data Sufficiency (DS3)


For DS butler Questions Click Here


to find the value of a^4 - b^4, we need values of both a and b or the relationship between them

Statement 1: NOT SUFFICIENT

Statement 2: NOT SUFFICIENT

Combining, we have both a and b so SUFFICIENT

Answer: Option C

CLICK HERE For Accessing 250+ FREE Videos on Number properties and DS and SUBSCRIBE the channel


1st Video solutions based Modular On-Demand QUANT Course: All Concepts | 2000+Qns | 20+ Tests |
Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub :)


Hi GMATinsight,

I think the answer to this should be B and not C. Could you please check?

Statement 2 tells us that b=a, and even though it does not tell us the magnitudes of a & b but the fact that they are equal is sufficient to cancel out their 4th powers, or any powers for that matter.

a⁴-b⁴ = b⁴-b⁴ = 0. Sufficient.

Posted from my mobile device
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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink] New post   20 Sep 2023, 09:33
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Re: What is the value of a^4 - b^4 ? (1) a = 3 (2) b = a [#permalink]
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