Answer:
40,000 is 39,265 rounded to the nearest ten thousands
Step-by-step explanation:
Let

In order to prove this by induction, we first need to prove the base case, i.e. prove that P(1) is true:

So, the base case is ok. Now, we need to assume
and prove
.
states that

Since we're assuming
, we can substitute the sum of the first n terms with their expression:

Which terminates the proof, since we showed that

as required
Should be the right answer ☺️