  A method is given for finding roots of a one-variable function using Taylor's
expansion of that function and fractional derivative calculated at a suitable
tangent point without using Newton's method, but is regarded as a variant of
Halley and Newton's one. Several examples regarding polynomials are stated as
well. Then, the given method is generalized to functions of several variables
belonging to an $n$-dimensional space and one example is given for optimization
and solution of a nonlinear system of equations by both our method and Gradient
Descent one. A comparison of our method is made with Gradient descent one for a
system of the functions of three variables. Our given method seems to be much
more rapidly than the Newton's one since by finding a suitable point on the
function's curve, the number of iterations is to be much less than Newton's
iterative steps. We also find order of fractional derivative, which corresponds
to equation's found root and compare tangent lines drawn at the root by both
fractional and classical derivatives. The methods given in this paper can be
used for optimization of function via fractional derivatives of order $\beta$.
