Maths Olympiad Prep

Library / /4 of 30

Algebra Difficulty 5.5 AIME, harder Find the answer

Find all non-negative solutions to the equation 2013x+2014y=2015z2013^x+2014^y=2015^z

A number or a short expression. Spacing and $ signs are ignored.

Solution

To solve the equation 2013x+2014y=2015z 2013^x + 2014^y = 2015^z for non-negative integer solutions (x,y,z)(x, y, z), we will explore small values manually and check if they satisfy the equation due to the rapid growth of exponential terms.

1. Initial Consideration:
Consider small non-negative integers for xx, yy, and zz to manually check for solutions.

2. **Checking x=0x = 0**:
- When x=0x = 0, the equation simplifies to:
1+2014y=2015z 1 + 2014^y = 2015^z
- Consider y=1y = 1:
1+2014=2015=20151 1 + 2014 = 2015 = 2015^1
This implies z=1z = 1.

3. Conclusion:
We found a solution (x,y,z)=(0,1,1)(x, y, z) = (0, 1, 1).

To verify that there are no other solutions, notice that for larger powers, the growth rate of 2015z2015^z quickly exceeds that of 2013x+2014y2013^x + 2014^y unless the base and powers are all particularly small or in balance, which we checked above.

Thus, the only non-negative solution is:
(0,1,1) \boxed{(0, 1, 1)}

Want a route through all this instead of an archive? The track puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.

Source: Omni-MATH, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.