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I did this the stupid way
Let integers = \(a\), \(b\)

\(\sqrt{a}-\sqrt{b}=\sqrt{15-10(2)^{1/2}}\)

Square both sides

\(a+b-2\sqrt{ab} = 15-10\sqrt{2}\)

\(a+b-2\sqrt{ab} = 15-2*5\sqrt{2}\)

From the equation above, we can say ->

\(a+b=15\)

\(\sqrt{ab}=5\sqrt{2}\)
\(\\
ab=50\\
\\
\)

\(a+\frac{50}{a}=15\)

\(a^2-15a+50=0\)

\(a=10\) or \(5\)

We assumed \(a\) is the larger integer (because the difference of the square roots of the two integers was positive)

This means \(a = 10\) and \(b = 5\)

square of the difference between these two integers \(= (a-b)^2 = (10-5)^2 = 5^2 = 25\)
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Honestly I ould not solve this question. Chose option C.
Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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sqrt(a)-sqrt(b)=sqrt(15-10sqrt(2))

Squaring the two terms:
a+b-2sqrt(ab)=15-10sqrt(2)=15-2sqrt(25*2)=15-2sqrt(50)

Equating the rational and irrational parts of the two terms:
a+b=15
2sqrt(ab)=2sqrt(50) -> ab=50

a=10 and b=5

(a-b)^2 = (10-5)^2 = 5^2 = 25

IMO C
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as per question we know Root(x) - Root(y) = Root(15-10root(2))
X and y are two integers.

after squaring both side we get x+y+2root(xy) = 15-10root(2)

now we can deduce that x+y = 15 and 2root(xy) = 10root(2) ==> root(xy) = 5root(2) ==> root(xy) = root(50).
xy = 50 and x+y = 15 so we now know integers are 5 and 10.
so we need |(x-y)^2| = 25
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The problem says that:

sqrt(X) - sqrt(Y) = sqrt(15-10*sqrt(2))

Let's square the two sides:

X + Y - 2*sqrt(XY) = 15 - 10*sqrt(2)
X + Y - 2*sqrt(XY) = 15 - 2*sqrt(50)

X + Y = 15
XY = 50

Solving: X=10 and Y=5 or X=5 and Y=10

But the problem says that sqrt(X) - sqrt(Y) is positive, so X=10 and Y=5

X - Y = 5
5^2 = 25

The right answer is C
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let integers a and b
so, [square_root a - square_root b] = [square_root of 15 - 10*square_root 2]
squaring both side,
a+b - 2*[square_root ab] = (15 - 10 *square_root 2) = (15 - 2* square_root 10 * 5)
after comparing both side we can see that, a = 10 and b =5

so, (a - b)^2 = (10 - 5)^2 = 25
option C
Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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for the GMAT Club Olympics Competition

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√15-10√2= -10 , square root = 100
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Lets assume the intergers are m and n
So root a - root b = \(\sqrt{15 - 10\sqrt{2}}\)
Square both sides you get (m−n)2=m+n−2mn=15−102
That means m+n =10
and mxn= 50
So m=5 or 10
and n= 5 or 10
Either way (m-n) = (10-5)= 25
ANS C
Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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for the GMAT Club Olympics Competition

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Let the two integers be x and y

\sqrt{x} - \sqrt{y} = \(\sqrt{15 - 10\sqrt{2}}\)

squaring on both sides, we get

x + y - 2\sqrt{xy} = \(\ 15 - 10\sqrt{2}\)

We can also write it as
x + y - 2\sqrt{xy} = \(\ 15 - 2\sqrt{50}\)

From this we can derive that
x + y = 15
xy = 50

From this we can get x =10 and y =5
So answer is (10-5)^2 = 25, Option C
Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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for the GMAT Club Olympics Competition

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Let the two integers be a and b
Given,
|√a - √b| = √15-10√2
Squaring both sides
a + b - 2√ab = 15 - 10√2
Comparing LHS with RHS, we get:
2√ab = 10√2
√ab = 5√2
√ab = √25*2
√ab = √50 and
a + b = 15
which means
a=10 and b=5
or a=5 and b=10
Q: (a-b)^2
(10-5)^2 or (5-10)^2
5^2 or (-5)^2
Both equals 25.

Option C

Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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for the GMAT Club Olympics Competition

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Given:
(√a)−(√b)=√[15−10(√2)]
Let’s try expressing the right side as:
√[15−10(√2)] = (√a)−(√b)

Square both sides:
a+b−2√ab = 15−10√2 ⇒a + b=15, ab=50
Solve the quadratic equation:

  • a, b are roots of t2−15t+50= t^2 - 15t + 50 = 0
  • After solving above mentioned quadratic equation we get roots are 10 & 5.
So:
  • a=10, b=5 ⇒a−b=5 ⇒(a−b)^2=25

So, the correct answer option is C.
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a^1/2 - b^1/2 = sqrt(15-10sqrt(2))
squaring both sides,
a+b-2sqrt(a*b)= 15 - 2*5*sqrt(2)

from here we get :
a+b=15 & ab=50
solving we get a = 10 or 5 & b =5 or 10
square of diff =25...ans (C)
Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


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for the GMAT Club Olympics Competition

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Numbers m and n

sqr of m - qsr of n = sqr of (15-10*sqr of (2))

Squaring both sides
m + n - 2 * sqr of (mn) = 15-10*sqr of (2)

Comparing both sides:
m + n = 15
2 * sqr of (mn) = 10*sqr of (2) = 2*5*sqr of (2) = 2*sqr of (2*5^2) = 2*sqr of (50)
mn=50

m=10 and n=5

difference=5
5^2=25

Correct answer is C
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Option C is our answer.

First lets understand the information mentioned in the question and then we will try to answer it.

[ltr]So the question tells us that "If the positive difference of the square roots of two integers is (15-10(2)^1/2)^1/2" and then asks us what is the square of the difference between these two integers. [/ltr]

Now lets assume the two integers to be x and y.

So as per the question (x)^1/2 - (y)^1/2 = (15-10(2)^1/2)^1/2

From here we can say that, (x)^1/2 = (15)^1/2
(y)^1/2 = (10*(2)^1/2)^1/2

As the question tells us that these values are for the square root of the number so to find the values of x and y we need to square them up.
After squaring both x and y their values will be, x = 15 and y = 10*(2)^1/2

Now the question asks us the "square of the difference between these two integers" which means we need to find the value of x^2 - y^2
Then x^2 = 225
y^2 = 200

=>The square of the difference between x and y = x^2 - y^2
=>The square of the difference between x and y = 225 - 200
=>The square of the difference between x and y = 25 (Option C)


Bunuel
If the positive difference of the square roots of two integers is \(\sqrt{15 - 10\sqrt{2}}\), what is the square of the difference between these two integers?

A. 9
B. 16
C. 25
D. 100
E. 225


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

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Lets assume two number be a and b, and a>b then,

√a - √b = √(15 - 10√2)
Squaring both side
a + b - 2√ab = 15 - 10√2
Comparing both side
a + b = 15
and
2√ab = 10√2
√ab = 5√2
Squaring both side
ab = 25*2 = 50

So, a + b = 15 and ab = 50
We think of it combination of and a and b as a = 10 and b = 5

and difference between a and b is 5 and its square is 25
Hence option C
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sqr(F)-sqr(S) = sqr(15-10*sqrt(2))

squaring
F+S-2*sqrt(FS) = 15-10*sqrt(2)
F+S-2*sqrt(FS) = 15-2*sqrt(50)

deducing
F+S = 15 and FS = 50

solving
F=10 and S=5

(F-S)^2=25

Answer C
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hi bb Bunuel my solution is correct , but not received kudos?
https://gmatclub.com/forum/gmat-club-ol ... l#p3600507
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