Verified answer

Successor of {1,2}

In this case A = {1,2} and so

The set containing A is { {1,2} }

So A U {A} = {1,2, {1,2} }

Successor of {1,2} = {1,2, {1,2} }

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successor of {5,{φ}}

In this case A = {5,{φ}}

{A} = { {5, {φ} } }

A U {A} = {5, {φ}, {5, {φ} } }

so

successor of {5,{φ}} = {5, {φ}, {5, {φ} } }

Possibly yeah