Ineed ..
proof it by mathematical induction
10+24+38++(14n-4)=7n²+3n

When proving something by induction, we have to establish a base case: we must prove that our assumption

is true for . We have

With the base case covered, we assume and prove that if holds, then follows. We have

Rewrite this expression as

Rearrange the terms as follows:

We already know (because we are assuming ) that

And when writing we wrote this equation, adding to both sides.

Recapping, we have assumed that , i.e. we have assumed that

Then we showed that can be written as

And so, if is true, must be true as well. This concludes the proof.

step-by-step explanation: 4 cause 2+2=4

the answer is 13 cm