The following is my code for solving a simple equation $$\sum_{n=1}^{10}100(1+x)^{4n}=5\cdot \sum_{n=1}^{5}100 (1+x)^{4n}$$ However, my code only returns one solution x=-1, assuming that I only want real solution. I know there is another solution close to $x=0.071773$.
I tried using x, [0 Inf] but the code just simply cannot find a solution.
A lot appreciated for any assistance.
syms x? Do you expect that there might be a closed-form expression for the solution ? I doubt it. Working with symbolic calculus might be inefficient. You'd rather define a function $F$ by : $$ F(x) = \sum_{n=1}^{10} 100(1+x)^{4n} - 5 \sum_{n=1}^{5} 100(1+x)^{4n} $$ and try to solve $F(x) = 0$ using, for example,fminsearchorfminunc. Also, you might want to simplify the expression of $F$ before implementing it in Matlab. – pitchounet May 22 '17 at 15:09fzerofunction finds $x=0.0717735$. Wolfram shows that all real-valued solutions except -1 do not have closed forms. They are (approximately) $-2.07177$ and $0.0717735$. – Arastas May 22 '17 at 15:30