Sum of squares

Algebra Level 2

Consider ( x + 2 y 8 ) 2 + ( x y + 1 ) 2 = 0 (x + 2y - 8)^2 + (x - y + 1)^2 = 0 where x x and y y are real numbers.

What must be the value of x?

2 3 Not enough information

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1 solution

Md Omur Faruque
Sep 2, 2015

As squares of real numbers are non-negative, for the sum of 2 2 squares to be 0 0 , they should both be 0 0 . So, we get, x + 2 y 8 = 0 x+2y-8=0 x y + 1 = 0 x-y+1=0

Solving these 2 2 equations we get, ( x , y ) ( 2 , 3 ) (x, y) \equiv (\color{#69047E} {\boxed {2}},3)

Thank you for the solution!

Bharath Murali - 5 years, 9 months ago

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I can see you're the author of this question. So, you knew the solution already. Any specific reason for the thanks?

MD Omur Faruque - 5 years, 9 months ago

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He's being friendly!

Calvin Lin Staff - 5 years, 9 months ago

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@Calvin Lin Reports, mails, comments, checking problems, giving feedbacks to solutions, slack. I wonder sometime, how do you manage to do all these everyday?

MD Omur Faruque - 5 years, 9 months ago

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@Md Omur Faruque Sleep is for the weak!

Calvin Lin Staff - 5 years, 9 months ago

Oh it's because I forgot to add the solution myself and you did that or me.

Bharath Murali - 5 years, 9 months ago

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@Bharath Murali Oh no! It's my pleasure. Just because you've posted the problem it's not mandatory for you to post a solution too.

MD Omur Faruque - 5 years, 9 months ago

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