roots([a, b, c-1])
your myfun doesn't make much sense:
y = a.*x.^2 + b.*x + c; %assuming a,b,c and x are scalar results in y being a scalar value
y(x) = 1; %set the element of array y (which has just one element) at index x (which may not even be integer) to 1
fsolve solves for 
not for 
. Again, the latter is easily rewrittent as 
but using fsolve, an iterative process that may return an approximation of the roots is a complete waste of time when there's a function for getting the roots of polynomial.
not for . Again, the latter is easily rewrittent as but using fsolve, an iterative process that may return an approximation of the roots is a complete waste of time when there's a function for getting the roots of polynomial.
