What will be T(n) after second step in a Recurrence Relation
What you get is correct, but you haven't gone further one more step, but two more steps.

T(n) = 2T(n - 1) + n

First :

T(n - 1) = 2T(n - 2) + (n - 1)

T(n) = 4T(n - 2) + 2(n - 1) + n

Second :

T(n - 2) = 2T(n - 3) + (n - 2)

T(n) = 8T(n - 3) + 4(n - 2) + 2(n - 1) + n

Third :

T(n - 3) = 2T(n - 4) + (n - 3)

T(n) = 16T(n - 4) + 8(n - 3) + 4(n - 2) + 2(n - 1) + n