4. Construct a recursive definition/function for the following functions: a. f (n) = 3 + 5 + ... + (2n + 3), where ne N b. f(n) = 0 + 1 + where ne N c. function "eq Tree" to check equality of 2 binary trees. Hint: two binary trees are equal, if the value of all corresponding nodes are equal. For example the following two trees are equal. b a C 2 +n, b a C