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If x and y both are integers, what is the value of x+y?

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If x and y both are integers, what is the value of x+y?  [#permalink]

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03 Nov 2018, 10:03
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Question Stats:

61% (01:39) correct 39% (01:31) wrong based on 85 sessions

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If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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03 Nov 2018, 10:18
1
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

Consider -

x = 1,y = 1,
x = -1,y = -1

Hence, E.
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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26 Nov 2018, 12:19
1
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

Dear Moderator,
Found this DS question, in the PS section of number properties , hope you will do the needful. Thank you.
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- Stne
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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26 Nov 2018, 12:23
stne wrote:
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

Dear Moderator,
Found this DS question, in the PS section of number properties , hope you will do the needful. Thank you.

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Moved to DS. Thank you.
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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26 Nov 2018, 17:10
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

From 1 : value of x & y can be +/-1
From 2: Same as 1 , two values of x & y +/- 1

IMO E
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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26 Nov 2018, 20:51
As the product of two integers is 1, we only two choices. Either -1 or 1.

Now consider x and y as -1.
Statement 1) True
Statement 2) True

x+y = -2

Now consider x and y as 1.
Statement 1) True
Statement 2) True

x+y = 2

Even after combining the statements we can't get a unique answer for x+y. So answer is E
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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27 Nov 2018, 04:06
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

From eqn1, we know x= y^-3
and from eqn2, y= x^-3

Combining, we get x=(( x^-3)^-3) or 1= x^5. This implies that x is positive. Hence, x+y should take the positive values of x and y respectively. (C)
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Re: If x and y both are integers, what is the value of x+y?  [#permalink]

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27 Nov 2018, 04:53
1
nishidesai wrote:
Abhi077 wrote:
If x and y both are integers, what is the value of x+y?

1) $$x(x^2y)$$ =1
2)$$y(y^2x)$$=1

From eqn1, we know x= y^-3
and from eqn2, y= x^-3

Combining, we get x=(( x^-3)^-3) or 1= x^5. This implies that x is positive. Hence, x+y should take the positive values of x and y respectively. (C)

You are wrong in the highlighted portion...$$(x^{-3})^{-3} = x^{-3*-3}=x^9.........x^8=1$$, so x can be 1 or -1
just substitute x and y as -1, this will also satisfy the equation.
$$x^{-3}x^{-3}=x^{-6}$$
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Re: If x and y both are integers, what is the value of x+y?   [#permalink] 27 Nov 2018, 04:53
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