Compute $v_x(t)$ and $v_y(t)$ by solving the differential equations in 1.
We can compute $v_x(t)$ and $v_y(t)$ by solving the differential equations in 1.
From
$$
v_x'' = -\frac{e^2B_z^2}{m^2}v_x
$$
and the initial conditions we find $v_x(t) = v_0 \cos(\omega_c t)$ with $\omega_c=eB_z/m$. From this we can derive $v_y(t)=-v_0\sin(\omega_c t)$.
and the initial conditions, we find $v_x(t) = v_0 \cos(\omega_c t)$ with $\omega_c=eB_z/m$. From this we can derive $v_y(t)=v_0\sin(\omega_c t)$.
We can now calculate the positions using $x(t)=x_0 + \int_0^t v_x(t')dt'$, and similarly for $y$, to find a parametric expression for the position of the particle
We can now calculate the particle position using $x(t)=x_0 + \int_0^t v_x(t')dt'$ (and similar for $y(t)$). We find a parametric expression for the position of the particle