The system model is given by

$m_1\frac{d^2{x}_1}{d{t}^2}+(k_1+k_2)x_1-k_2{x}_2=F_1(t)$

$m_2\frac{d^2{x}_2}{d{t}^2}-k_2{x}_1+(k_2+k_3)x_2=F_2(t)$

where $F_1(t)$ and $F_2(t)$ are the inputs to the system. Find the transfer function $x_1\frac{s}{F_1}(s).$

$\frac{(m_1{s}^2+k_1+k_2)}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$

$\frac{k_3}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$

$\frac{k_1+k_2}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$

$\frac{k_2}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$

$\frac{(m_2{s}^2+k_2+k_3)}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$

$\frac{k_2+k_3}{(m_1{s}^2+k_1+k_2)(m_2{s}^2+k_2+k_3)-k_2^2}$