A particular spring does not obey Hooke's law (F(x) = -kx), but rather is described by F(x)=-k x-kax? x is the displacement of the spring from equilibrium and the constants k, and k2 are given below. Randomized Variables ki = 6.9 N/m k2 = 9.9 N/m2 * 50% Part (a) Input an expression for the potential energy of the spring as a function of position. Part (b) What is the magnitude of the restoring force of this spring, in newtons, if it is stretched 26.5 cm from equilibrium?