differential equation

hello everybody,

its my first time here. I have a little problem with differential
equations :

How can I solve a differential system like this or does anybody know
the solution ?

x_i=x_i(t) with i =1,2,3
a_i,b_i,c_i : constants

(1) d^2x_1/dt^2 = a_1*x_1 + b_1 + c_1* x_2*x_3

(2) d^2x_2/dt^2 = a_2*x_2 + b_2 + c_2* x_1*x_3

(3) d^2x_3/dt^2 = a_3*x_3 + b_3 + c_3* x_2*x_3

many thanks in advance !

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