Suppose the rule ₹[ƒ(−2,−1)+4ƒ(−2,0)+ ƒ(−2,1)+ƒ(2,−1)+4ƒ(2,0)+ƒ(2,1)] is applied to 12 solve ƒ(x, y) dx dy. Describe the form of the function ƒ(x, y) that are integrated -1-2 exactly by this rule and obtain the result of the integration by using this form.