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555-605 (Medium)|   Algebra|      
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Bunuel
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What is the value of (a + b)^2 ? 05 Nov 2014, 08:11
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

25% (medium)

Question Stats:

75% (01:27) correct 25% (01:49) wrong based on 508 sessions

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What is the value of (a + b)^2 ?

(1) a = 15/b
(2) (a – b)^2 = 4
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C
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anupamadw
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What is the value of (a + b)^2 ? 06 Nov 2014, 06:32
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Bunuel

Tough and Tricky questions: Algebra.



What is the value of (a + b)^2 ?

(1) a = 15/b
(2) (a – b)^2 = 4

Kudos for a correct solution.
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What is the value of (a + b)^2 ?
(a+b)^2 = a^2+b^2+2ab

(1) a = 15/b --> ab =15 insuff

(2) (a – b)^2 = 4
a^2+b^2 = 2ab+4 insuff

(a+b)^2 = a^2+b^2+2ab
= 2ab+4+2ab ( from stmnt2)
= 4ab+4
= 4*15 ( from stmnt1)

IMO C, could you please confirm the answer?
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BassanioGratiano
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What is the value of (a + b)^2 ? 06 Nov 2014, 17:39
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anupamadw
Bunuel

Tough and Tricky questions: Algebra.



What is the value of (a + b)^2 ?

(1) a = 15/b
(2) (a – b)^2 = 4

Kudos for a correct solution.



What is the value of (a + b)^2 ?
(a+b)^2 = a^2+b^2+2ab

(1) a = 15/b --> ab =15 insuff

(2) (a – b)^2 = 4
a^2+b^2 = 2ab+4 insuff

(a+b)^2 = a^2+b^2+2ab
= 2ab+4+2ab ( from stmnt2)
= 4ab+4
= 4*15 ( from stmnt1)

IMO C, could you please confirm the answer?
Show more

Thanks for step the by step. Just to point out you forgot to add the +4 to your last step. Other than that, thank you so much!
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anupamadw
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GMAT 1: 630 Q48 V29
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What is the value of (a + b)^2 ? 06 Nov 2014, 22:54
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BassanioGratiano
anupamadw
Bunuel

Tough and Tricky questions: Algebra.



What is the value of (a + b)^2 ?

(1) a = 15/b
(2) (a – b)^2 = 4

Kudos for a correct solution.



What is the value of (a + b)^2 ?
(a+b)^2 = a^2+b^2+2ab

(1) a = 15/b --> ab =15 insuff

(2) (a – b)^2 = 4
a^2+b^2 = 2ab+4 insuff

(a+b)^2 = a^2+b^2+2ab
= 2ab+4+2ab ( from stmnt2)
= 4ab+4
= 4*15 ( from stmnt1)

IMO C, could you please confirm the answer?

Thanks for step the by step. Just to point out you forgot to add the +4 to your last step. Other than that, thank you so much!
Show more


:) Thanks for pointing out, but I am not sure about OA.
So let's wait for Bunuel to confirm answer.
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Bunuel
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What is the value of (a + b)^2 ? 10 Nov 2014, 05:26
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anupamadw
BassanioGratiano
anupamadw




What is the value of (a + b)^2 ?
(a+b)^2 = a^2+b^2+2ab

(1) a = 15/b --> ab =15 insuff

(2) (a – b)^2 = 4
a^2+b^2 = 2ab+4 insuff

(a+b)^2 = a^2+b^2+2ab
= 2ab+4+2ab ( from stmnt2)
= 4ab+4
= 4*15 ( from stmnt1)

IMO C, could you please confirm the answer?

Thanks for step the by step. Just to point out you forgot to add the +4 to your last step. Other than that, thank you so much!


:) Thanks for pointing out, but I am not sure about OA.
So let's wait for Bunuel to confirm answer.
Show more
_____________
The OA is C.
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akumar5
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What is the value of (a + b)^2 ? 10 Nov 2014, 06:16
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Since we know (a+b)^2-(a-b)^2=4ab

so we need values both for ab and (a-b)

1) a=15/b
2)(a-b)^2=4

from above two options we can have the required value for (a+b)^2

ANSWER IS C
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What is the value of (a + b)^2 ? 07 Mar 2023, 20:16
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We can determine the value of (a + b)^2 in one of three ways: by figuring out the sum of a and b, by determining what a and b are separately, or by determining the value of a^2 + 2ab + b^2 (which is the quadratic form of our product of factors).

(1) INSUFFICIENT: After multiplying both sides by b, we can determine that ab = 15, but we know nothing else.

(2) INSUFFICIENT: If we FOIL (a – b)2 we can learn that a2 – 2ab + b2 = 4. However, this does not allow us to determine the sum of a and b, the respective values of a and b individually, or the value of a2 + 2ab + b2.

(1) AND (2) SUFFICIENT: Statement 1 tells us ab = 15. If we substitute this into the quadratic equation from the second statement, we can determine the value of a^2 + b^2 in the following manner:

a^2 – 2(15) + b^2 = 4
a^2 – 30 + b^2 = 4
a^2 + b^2 = 34

If we know the value of a^2 + b^2, and the value of ab, we can determine the value of a^2 + 2ab + b^2.
a^2 + 2ab + b^2 = a^2 + b^2 + 2ab = 34 + 2(15) = 64

The correct answer is C
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