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Algebra Difficulty 6.1 National olympiad Prove it Ukraine

Solve the equation:
12014x+12015x+1+12016x+2=12015x1+12016x2+12017x3 \frac{1}{\sqrt{2014}-\sqrt{x}} + \frac{1}{\sqrt{2015}-\sqrt{x+1}} + \frac{1}{\sqrt{2016}-\sqrt{x+2}} = \frac{1}{\sqrt{2015-x}-\sqrt{1}} + \frac{1}{\sqrt{2016-x}-\sqrt{2}} + \frac{1}{\sqrt{2017-x}-\sqrt{3}}

Solution

Multiply both numerator and denominator by the conjugate:
2014+x2014x+2015+x+12015(x+1)+2016+x+22016(x+2)=2015x+1(2015x)1+2016x+2(2016x)2+2017x+3(2017x)3 \frac{\sqrt{2014+\sqrt{x}}}{2014-x} + \frac{\sqrt{2015+\sqrt{x+1}}}{2015-(x+1)} + \frac{\sqrt{2016+\sqrt{x+2}}}{2016-(x+2)} = \frac{\sqrt{2015-x+\sqrt{1}}}{(2015-x)-1} + \frac{\sqrt{2016-x+\sqrt{2}}}{(2016-x)-2} + \frac{\sqrt{2017-x+\sqrt{3}}}{(2017-x)-3}
After multiplying by the common denominator we have:
2014+x+2015+x+1+2016+x+2=2015x+1+2016x+2+2017x+3, \sqrt{2014+\sqrt{x}} + \sqrt{2015+\sqrt{x+1}} + \sqrt{2016+\sqrt{x+2}} = \sqrt{2015-x} + \sqrt{1} + \sqrt{2016-x} + \sqrt{2} + \sqrt{2017-x} + \sqrt{3},

1) x=1x=1 is the solution of the equation:
2014+1+2015+2+2016+3=2014+1+2015+2+2016+3. \sqrt{2014} + \sqrt{1} + \sqrt{2015} + \sqrt{2} + \sqrt{2016} + \sqrt{3} = \sqrt{2014} + \sqrt{1} + \sqrt{2015} + \sqrt{2} + \sqrt{2016} + \sqrt{3}.

2) Denote S=2014+1+2015+2+2016+3S = \sqrt{2014} + \sqrt{1} + \sqrt{2015} + \sqrt{2} + \sqrt{2016} + \sqrt{3}. For x>1x > 1 we have
2014+x+2015+x+1+2016+x+2>2014+1+2015+2+2016+3=S. \sqrt{2014} + \sqrt{x} + \sqrt{2015} + \sqrt{x+1} + \sqrt{2016} + \sqrt{x+2} > \sqrt{2014} + \sqrt{1} + \sqrt{2015} + \sqrt{2} + \sqrt{2016} + \sqrt{3} = S.
So the left-hand side is greater than SS, and in the same way we analyze the right-hand side:
2015x+1+2016x+2+2017x+3<2014+1+2015+2+2016+3=S. \sqrt{2015-x} + \sqrt{1} + \sqrt{2016-x} + \sqrt{2} + \sqrt{2017-x} + \sqrt{3} < \sqrt{2014} + \sqrt{1} + \sqrt{2015} + \sqrt{2} + \sqrt{2016} + \sqrt{3} = S.
So in this interval there are no roots. The same holds for x<1x < 1.

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Source: MathNet, licensed CC-BY-4.0. Statement and solution reproduced as published; topic and difficulty added by this site.