hello Physics Forum team i need help with nuclear physics homework due in 5hours.

stable nuclei: given the semi-empirical formula for the total energy of a nucleus to be : E=(Zm_p+Nm_n)c^2-(a_1*A-a_2*A^(2/3)-a_3*Z^3*A^(-1/3)-a_4(A-2Z)^2*A^(-1)+a_5*A^(1/2))c^2

show that, for a given value of A, the minimum energy occurs when: Z=1/2 A (4a_4+m_n-m_p)/(4a_4+a_3 A^(2⁄3) )