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(3^(1/2) + 2)(3^(1/2) - 2) =

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Bunuel
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(3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   08 Oct 2018, 02:39
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A
B
C
D
E

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92% (00:20) correct 8% (00:32) wrong based on 620 sessions
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\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)


A. \(\sqrt{3}-4\)

B. \(\sqrt{6}-4\)

C. -1

D. 1

E. 2
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C
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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   08 Oct 2018, 02:56
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Bunuel wrote:
\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)


A. \(\sqrt{3}-4\)

B. \(\sqrt{6}-4\)

C. -1

D. 1

E. 2


Square of a difference = a^2 - b^2 = (a-b)(a+b)

3 - 4 = -1

Answer choice C

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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   08 Oct 2018, 08:58
Bunuel wrote:
\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)


A. \(\sqrt{3}-4\)

B. \(\sqrt{6}-4\)

C. -1

D. 1

E. 2


\((\sqrt{3} + 2)(\sqrt{3} - 2)\)

\(= \sqrt{3}*\sqrt{3} - 2*2\)

\(= 3 - 4\)

\(= -1\),Answer must be (C)
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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   15 Sep 2019, 05:00
Bunuel wrote:
\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)


A. \(\sqrt{3}-4\)

B. \(\sqrt{6}-4\)

C. -1

D. 1

E. 2


\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)
= 3-4 =-1

IMO C

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BrentGMATPrepNow
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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   01 Sep 2020, 10:58
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Bunuel wrote:
\((\sqrt{3} + 2)(\sqrt{3} - 2)=\)


A. \(\sqrt{3}-4\)

B. \(\sqrt{6}-4\)

C. -1

D. 1

E. 2


In case you didn't catch the difference of squares, here's another approach that will still help you reach the correct answer:

------ASIDE------------------------
By test day, all students should have the following approximations memorized:
√2 ≈ 1.4
√3 ≈ 1.7
√5 ≈ 2.2
-------------------------------------
When we replace the given values we get:
\((\sqrt{3} + 2)(\sqrt{3} - 2)≈(1.7 + 2)(1.7 - 2)≈(3.7)(-0.3)≈-1.1\)
So the correct answer must be approximately -1.1

Let's check the answer choices...
A. \(\sqrt{3}-4≈1.7-4≈-2.3\)
No good. Eliminate

B. \(\sqrt{6}-4\)
Since √4 = 2 and √9 = 3, √6 is about 2.4
So, \(\sqrt{6}-4≈2.4-4≈1.6\)
This is pretty close to -1.1, so we'll keep it for now

C. -1
This is closer to -1.1
Keep for now

D. 1
No good. Eliminate

E. 2
No good. Eliminate

So, we are down to answer choices B and C
Since C is closer, we'll take that.

Cheers,
Brent
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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   02 Sep 2020, 05:55
The answer is C
It is a simple question which uses the formula a+b)(a-b) equals a2+b2
By using this formula we can get the answer

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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink] (3^(1/2) + 2)(3^(1/2) - 2) =   15 Jul 2023, 02:34
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Re: (3^(1/2) + 2)(3^(1/2) - 2) = [#permalink]
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