Problem: For any real number a, let ⌊a⌋ denote the greatest integer not exceeding a. In positive real numbers solve the following equation n+⌊n⌋+⌊3n⌋=2014
Solutions — 2
Solution 1
Solution: Obviously n must be a positive integer. Now note that 442=1936<2014<2025=452 and 123<1900<2014<133. If n<1950 then 2014=n+⌊n⌋+⌊3n⌋<1950+44+12=2006, a contradiction! So n≥1950. Also if n>2000 then 2014=n+⌊n⌋+⌊3n⌋>2000+44+12=2056, a contradiction! So 1950≤n≤2000, therefore ⌊n⌋=44 and ⌊3n⌋=12. Plugging that into the original equation we get: n+⌊n⌋+⌊3n⌋=n+44+12=2014 From which we get n=1958.
Solution 2
Solution: Obviously n must be a positive integer. Since n≤2014, n<45 and 3n<13. From n=2014−⌊n⌋−⌊3n⌋>2014−45−13=1956, n>44 and 3n>12, thus ⌊n⌋=44 and ⌊3n⌋=12 and n=2014−⌊n⌋−⌊3n⌋=2014−44−12=1958.
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