The problem of the last contest was:
x² = -1
The solution to this is not to hard, although it is still often teached in school that this has no solution:
x² = -1 | √
↓
x = √-1
And that's mostly it. Now you just need to know that i is defined as:
i = √-1
↓
x = i
There also are 2 other possible solutions which would need knowledge about quaternions(the 4d version of complex number with i, j and k):
x = j and x = k
The last two solutions are less popular and no one got that.
The first solution was chosen correctly by 2 people:
So I put their names into a self-written random selector:
Congratulations
The next contest will start tomorrow and will be slightly different.