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Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0

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Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0  [#permalink]

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New post 18 Nov 2019, 02:00
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A
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C
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E

Difficulty:

  35% (medium)

Question Stats:

72% (00:53) correct 28% (01:20) wrong based on 36 sessions

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Senior Manager
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Joined: 25 Jul 2018
Posts: 395
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Re: Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0  [#permalink]

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New post 18 Nov 2019, 02:10
Is ab <0?

(Statement1):
\(a^{4}*b^{9}*c^{2} <0\)
—> we can simplify —> b <0

a can be positive or negative
Insufficient


Statement2): \(a(bc)^{6} > 0\)
—> we can simplify —> a > 0

b can be positive or negative
Insufficient

Taken together 1&2,
a > 0 and b <0
—> ab is always less than zero
(ab <0)

Sufficient

The answer is C

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Manager
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Posts: 122
Location: India
Concentration: General Management, Strategy
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Re: Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0  [#permalink]

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New post 25 Nov 2019, 10:41
lacktutor wrote:
Is ab <0?

(Statement1):
\(a^{4}*b^{9}*c^{2} <0\)
—> we can simplify —> b <0

a can be positive or negative
Insufficient


Statement2): \(a(bc)^{6} > 0\)
—> we can simplify —> a > 0

b can be positive or negative
Insufficient

Taken together 1&2,
a > 0 and b <0
—> ab is always less than zero
(ab <0)

Sufficient

The answer is C

Posted from my mobile device




Can you please explain why b <0 in (1) and a > 0 in (2) :cry:
Senior Manager
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Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0  [#permalink]

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New post 25 Nov 2019, 11:13
1
merajul wrote:
lacktutor wrote:
Is ab <0?

(Statement1):
\(a^{4}*b^{9}*c^{2} <0\)
—> we can simplify —> b <0

a can be positive or negative
Insufficient


Statement2): \(a(bc)^{6} > 0\)
—> we can simplify —> a > 0

b can be positive or negative
Insufficient

Taken together 1&2,
a > 0 and b <0
—> ab is always less than zero
(ab <0)

Sufficient

The answer is C

Posted from my mobile device




Can you please explain why b <0 in (1) and a > 0 in (2) :cry:


Hi,
—> Dividing (or Multiplying)the both sides by the same positive number does not change the sign of an inequality.
—> (Statement1): The exponents of ‘a’ and ‘c’ are even —>\(a^{4}\) and \(c^{2}\) are positive numbers.
—> you can divide both sides by both positive numbers, it does not change the sign and you’ll get b< 0.

The same as statement2
Hope it helps
Manager
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Joined: 05 Oct 2014
Posts: 122
Location: India
Concentration: General Management, Strategy
GMAT 1: 580 Q41 V28
GPA: 3.8
WE: Project Management (Energy and Utilities)
Re: Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0  [#permalink]

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New post 25 Nov 2019, 11:18
lacktutor wrote:
merajul wrote:
lacktutor wrote:
Is ab <0?

(Statement1):
\(a^{4}*b^{9}*c^{2} <0\)
—> we can simplify —> b <0

a can be positive or negative
Insufficient


Statement2): \(a(bc)^{6} > 0\)
—> we can simplify —> a > 0

b can be positive or negative
Insufficient

Taken together 1&2,
a > 0 and b <0
—> ab is always less than zero
(ab <0)

Sufficient

The answer is C

Posted from my mobile device




Can you please explain why b <0 in (1) and a > 0 in (2) :cry:


Hi,
—> Dividing (or Multiplying)the both sides by the same positive number does not change the sign of an inequality.
—> (Statement1): The exponents of ‘a’ and ‘c’ are even —>\(a^{4}\) and \(c^{2}\) are positive numbers.
—> you can divide both sides by both positive numbers, it does not change the sign and you’ll get b< 0.

The same as statement2
Hope it helps


Ah!!! now able to understand. Thank You
GMAT Club Bot
Re: Is ab < 0? (1) a^4b^9c^2 < 0 (2) a(bc)^6 > 0   [#permalink] 25 Nov 2019, 11:18
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