Hooke's law is applicable to idealized (linear) springs that are not stretched or compressed too far. Consider a nonlinear spring whose restoring force is given by F(x) = 18x - 0.3x3, for |x| ≤ 9. How much work is done in stretching the spring from its equilibrium position (x = 0) to x = 1? Round to two decimal places when appropriate.
◦ 473.85 J
◦ 17.7 J
◦ 8.93 J
◦ 236.93 J