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If n is the square of a positive integer, which of the following must

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If n is the square of a positive integer, which of the following must  [#permalink]

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New post 09 Nov 2015, 22:59
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If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. \(\sqrt{n} + 1\)

B. \(n + 1\)

C. \(n^2 + 1\)

D. \(n + 2\sqrt{n} + 1\)

E. \(n^2 + 2n + 1\)

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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 10 Nov 2015, 01:53
1
Let a= +ve integer such that
n= a^2
(a+1)= next +ve integer
(a+1)^2 = a^2 + 1 + 2a

and a=n^(1/2)
Therefore ,
(a+1)^2=n+1+2*n^(1/2)
Answer D

Alternatively,
we can take values
let n= 4 =a^2
=> a= 2
(a+1)=3^2 = 9
now checking the choices
A. √n + 1
= 2+1 =3
B. n + 1
= 4+1 =5
C. n^2 + 1
= 16+1 =17
D. n + 2√n + 1
= 4+ 2*2 +1 = 9
Answer D
E. n^2 + 2n + 1
= 16+ 8 + 1 =25
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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 10 Nov 2015, 11:26
1
If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

n = (x)^2 where x is a positive integer
To calculate -
(x+1)^2 = x^2 + 2x + 1
root(n) = x

Ans - n + 2 root(n) + 1
This should be D
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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 08 Oct 2016, 14:59
Bunuel wrote:
If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. √n + 1
B. n + 1
C. n^2 + 1
D. n + 2√n + 1
E. n^2 + 2n + 1



next positive integer is sqrt(n)+1.
square of this number is [sqrt(n)+1]^2
the result is definitely a number with an "n" not squared not under radical
A,C, E out
B can't be the answer
so it must be D.

not even needed to square everything...
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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 16 Oct 2016, 14:43
Bunuel wrote:
If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. √n + 1
B. n + 1
C. n^2 + 1
D. n + 2√n + 1
E. n^2 + 2n + 1


n is +ve integer

n = x^2 thus sqrt n = x , (x+1)^2 = x^2 + 2x+1 , substitute n^2+2sqrtn+1
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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 16 Oct 2016, 23:45
1
Bunuel wrote:
If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. √n + 1
B. n + 1
C. n^2 + 1
D. n + 2√n + 1
E. n^2 + 2n + 1


Plug in some value and check -

Let n = 1 ( least number )
Square of the next positive integer is 4

Now, check the options : Only (D) and (E) satisfies

Check using one more square number to confirm the answer

Let n = 4 ( least number )
Square of the next positive integer is 9

Now, check the options : Only (D) satisfies

Hence answer must be option (D)

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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 13 Apr 2017, 04:43
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Option D

\(n = K^2\); K>0 and Integer

\((K+1)^2 = K^2 + 2K + 1 = n + 2\sqrt{n} + 1\)
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If n is the square of a positive integer, which of the following must  [#permalink]

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New post 26 May 2017, 09:37
Skywalker18 wrote:
Let a= +ve integer such that
n= a^2
(a+1)= next +ve integer
(a+1)^2 = a^2 + 1 + 2a

and a=n^(1/2)
Therefore ,
(a+1)^2=n+1+2*n^(1/2)
Answer D

Alternatively,
we can take values
let n= 4 =a^2
=> a= 2
(a+1)=3^2 = 9
now checking the choices
A. √n + 1
= 2+1 =3
B. n + 1
= 4+1 =5
C. n^2 + 1
= 16+1 =17
D. n + 2√n + 1
= 4+ 2*2 +1 = 9
Answer D
E. n^2 + 2n + 1
= 16+ 8 + 1 =25



This question makes no sense to me . Isn't 5 the next positive integer after 4, and 5^2=25. I definitely did everything you prescribed on my first attempt at this question. Could you elaborate . Answer seems like it should be E to me . It always give you the square of the next positive integer . I am completely perplexed here. Think I'm just being dumb. Thanks !
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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 26 May 2017, 09:48
2
1
NanaA wrote:
Skywalker18 wrote:
Let a= +ve integer such that
n= a^2
(a+1)= next +ve integer
(a+1)^2 = a^2 + 1 + 2a

and a=n^(1/2)
Therefore ,
(a+1)^2=n+1+2*n^(1/2)
Answer D

Alternatively,
we can take values
let n= 4 =a^2
=> a= 2
(a+1)=3^2 = 9
now checking the choices
A. √n + 1
= 2+1 =3
B. n + 1
= 4+1 =5
C. n^2 + 1
= 16+1 =17
D. n + 2√n + 1
= 4+ 2*2 +1 = 9
Answer D
E. n^2 + 2n + 1
= 16+ 8 + 1 =25



This question makes no sense to me . Isn't 6 the next positive integer after 4, and 6^2=36. I definitely did everything you prescribed on my first attempt at this question. Could you elaborate . Think I'm just being dumb. Thanks !


If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. \(\sqrt{n} + 1\)

B. \(n + 1\)

C. \(n^2 + 1\)

D. \(n + 2\sqrt{n} + 1\)

E. \(n^2 + 2n + 1\)

n is the square of a positive integer. Say that positive integer is x. So, we are given that \(n = x^2\). Notice that from this it follows that \(x=\sqrt{n}\)

Which of the following must be equal to the square of the next positive integer?

The next positive integer is x + 1. Its square = \((x+1)^2=x^2+2x+1\).

Substitute the values of x^2 and x from above to get: \((x+1)^2=x^2+2x+1=n+2\sqrt{n}+1\).

Answer: D.
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New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: If n is the square of a positive integer, which of the following must  [#permalink]

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New post 17 Jul 2018, 16:45
Bunuel wrote:
If n is the square of a positive integer, which of the following must be equal to the square of the next positive integer?

A. \(\sqrt{n} + 1\)

B. \(n + 1\)

C. \(n^2 + 1\)

D. \(n + 2\sqrt{n} + 1\)

E. \(n^2 + 2n + 1\)


We can let n = k^2 where k is a positive integer, we see that the square of the next positive integer is
(k + 1)^2 = k^2 + 2k + 1. Since n = k^2, so k = √n. Therefore, in terms of n, the square of the next positive integer is n + 2√n + 1.

Answer: D
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Re: If n is the square of a positive integer, which of the following must &nbs [#permalink] 17 Jul 2018, 16:45
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