(c0 * k * vt + k * qm * vm + vt - sqrt(c0 ** 2 * k ** 2 * vt ** 2 - 2 * c0 *
    k ** 2 * qm * vm * vt + 2 * c0 * k * vt ** 2 + k ** 2 * qm ** 2 * vm **
    2 + 2 * k * qm * vm * vt + vt ** 2)) / (2 * k * vm)
sympy: order of result from solving a quadratic equation