I have no idea how you could solve a 360 degre polynomial equation. I know that wolfram doesn't have enough computer time for free users and I dont have maple/mathlab/etc.. on this computer..
Altough I guess you could try brute forcing it. since they want the answer rounded to 2 decimal. it wouldn't be too long to find an answer that fit there.
so I did take 10 min to write a code in C# and took a minute to find a solution that worked.
the answer should be
I added the code below its very basic in C#.
edit: I substitued my value in soroban equation and it does work!
const int NUMBER_MONTH = 360
const float MONTLY_PAYMENT = 450f;
const float THE_NUMBER_WE_LOOKING_FOR= 0.49804f;
static void Main(string args)
float Tableau = new float[NUMBER_MONTH];
Tableau = 450f;
for (int i = 0; i < NUMBER_MONTH-1; i++)
Tableau[i + 1] = FonctionRecursive(Tableau[i]);
static float FonctionRecursive(float val)