SOLUTION: a²+b²=25 a³+b³=91

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Question 691044: a²+b²=25
a³+b³=91

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
I am not sure if the problem is meant as a system of non-linear equations, or a simpler problem, looking for integers that satisfy each (or both) equations.

The most popular of Pythagorean triples (and the only one I remember) is
(3,4,5) with 3%5E2%2B4%5E2=5%5E2 or 3%5E2%2B4%5E2=25.
So the only answer to a%5E2%2Bb%5E2=25 with whole numbers is highlight%283%5E2%2B4%5E2=5%5E2%29. If we allow negative numbers, there are other integer solutions to just that equation (we just cahnge the signs for a and/or b).

Curiously, the same numbers 3 and 4 are a solution to a%5E3%2Bb%5E3=91,
3%5E3%2B4%5E3=27%2B64=91.
So you could say that the pair (3,4) is the only integer solution to the system
system%28a%5E2%2Bb%5E2=25%2Ca%5E3%2Bb%5E3=91%29

If we wanted all real numbers that are solutions to the system, we would have to look for two more points where the graphs intersect for
x%5E2%2By%5E2=25 (circle with radius 5) and
x%5E3%2By%5E3=91 <--> y=root%283%2C91-x%5E3%29 (a snakey downwards line).