An unusual spring has a restoring force of magnitude F = (2.00 N/m)x + (1.00 N/m2)x 2, where x is the stretch of the spring from its equilibrium length. A 3.00-kg object is attached to this spring and released from rest after stretching the spring 1.65 m. If the object slides over a frictionless horizontal surface, how fast is it moving when the spring returns to its equilibrium length?