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If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0

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Bunuel
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If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink] New post   18 Mar 2020, 09:14
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If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
(2) a^3 > 0
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A
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Kinshook
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Re: If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink] New post   18 Mar 2020, 09:49
Bunuel wrote:
If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
(2) a^3 > 0


Asked: If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
|a| = 9
3b - 9 = 27
3b = 36
b = 12
SUFFICIENT

(2) a^3 > 0
|a| is unknown
3b - |a| = 27
3b = 27 + |a|
3b is unknown
b is unknown
NOT SUFFICIENT

IMO A
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Re: If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink] New post   09 Apr 2020, 01:50
Kinshook wrote:
Bunuel wrote:
If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
(2) a^3 > 0


Asked: If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
|a| = 9
3b - 9 = 27
3b = 36
b = 12
SUFFICIENT

(2) a^3 > 0
|a| is unknown
3b - |a| = 27
3b = 27 + |a|
3b is unknown
b is unknown
NOT SUFFICIENT

IMO A


Hi Kinshook,

I am bit confused in the first part. Why did you consider mod x as only +9 and not -9? Since x = +-9.

for, x^3 > 0, x must be positive.

Combining 1 & 2 we can say that x = 9 so we get the value of b.

Where am I making the mistake?

- Pradeep
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Krishishere
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If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink] New post   28 Oct 2020, 03:53
Pradeep, condition 1 is sufficient even if you plug in both values of |a|.

Pksri wrote:
Kinshook wrote:
Bunuel wrote:
If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
(2) a^3 > 0


Asked: If 3b − |a| = 27, what is the value of b?

(1) a^2 = 81
|a| = 9
3b - 9 = 27
3b = 36
b = 12
SUFFICIENT

(2) a^3 > 0
|a| is unknown
3b - |a| = 27
3b = 27 + |a|
3b is unknown
b is unknown
NOT SUFFICIENT

IMO A


Hi Kinshook,

I am bit confused in the first part. Why did you consider mod x as only +9 and not -9? Since x = +-9.

for, x^3 > 0, x must be positive.

Combining 1 & 2 we can say that x = 9 so we get the value of b.

Where am I making the mistake?

- Pradeep
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xabi14
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Re: If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink] New post   29 Nov 2020, 06:20
Plugging in results in two values, while DS requires only one outcome as sufficient? CMIIW

[quote="Krishishere"]Pradeep, condition 1 is sufficient even if you plug in both values of |a|.

[quote="Pksri"]
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Re: If 3b − |a| = 27, what is the value of b? (1) a^2 = 81 (2) a^3 > 0 [#permalink]
29 Nov 2020, 06:20
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Bunuel
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