Solve the equation: 2014−x1+2015−x+11+2016−x+21=2015−x−11+2016−x−21+2017−x−31
Solution
Multiply both numerator and denominator by the conjugate: 2014−x2014+x+2015−(x+1)2015+x+1+2016−(x+2)2016+x+2=(2015−x)−12015−x+1+(2016−x)−22016−x+2+(2017−x)−32017−x+3 After multiplying by the common denominator we have: 2014+x+2015+x+1+2016+x+2=2015−x+1+2016−x+2+2017−x+3,
1) x=1 is the solution of the equation: 2014+1+2015+2+2016+3=2014+1+2015+2+2016+3.
2) Denote S=2014+1+2015+2+2016+3. For x>1 we have 2014+x+2015+x+1+2016+x+2>2014+1+2015+2+2016+3=S. So the left-hand side is greater than S, and in the same way we analyze the right-hand side: 2015−x+1+2016−x+2+2017−x+3<2014+1+2015+2+2016+3=S. So in this interval there are no roots. The same holds for x<1.
Looking for a route rather than an archive? The track puts 2,000
problems in a working order, from AMC 10 level to the IMO shortlist.
Source: MathNet,
licensed CC-BY-4.0.
Statement and solution reproduced as published; topic and difficulty added by this site.