solving 3 equations with 3 unknowns

Question

How can i solve three equations with three unknows in C#, in matlab for example i use the fsolve, is there exist such a function in C#. the equations are the following: a(1)*vecx(1)+a(2)*vecx(2)+a(3)*vecx(3) ; a(1)*((Y1(4)*z(2))-(Y1(2)*z(4)))-a(2)*((X1(4)*z(2))-(X1(2)*z(4))) +a(3)*((X1(4)*Y1(2))-(X1(2)*Y1(4))); a(1)^2+a(2)^2+a(3)^2-1; with a(1), a(2) and a(3) are the unknowns. thank you