Differentiating with respect to x and y, and equating the differential coefficients to zero, we have
Σ (F₁ - x - y R₁) = 0,
Σ R₁(F₁ - x - y R₁) = 0.
This gives two equations for the determination of x and y.
Suppose, as is usually the case, the loads be of the form,
N, 2N, 3N, 4N &c. mN,
and making
A = F₁ + F₂ + F₃ + &c. + Fₘ
B = F₁ +2F₂ + 3F₃ + &c. + mFₘ,
we have the equations