An applied force varies with position according to F = k1*x^n - k2, where n = 3, k1 = 3.4 N/m^3, and k2 = 53N.
Substituting the values of k1, k2 and n gives F = 3.4*x^3 - 53
The work done by a force F is the product of the force and the displacement due to the force.
Here, as the force is not constant, it is the definite integral of (3.4*x^3 - 53) dt from x = 4.73 to x = 13
This is equal to:
(3.4/4)*(13^4 - 4.73^4) - 53(13 - 4.73)
=> 23413.07 J
=> 23.413 kJ
The work done by the force is equal to 23.413 kJ