Ali is planning to keep fit through practicing push-ups for 21 days. on the first day, he can only do 14 push-ups in a minute. He plans to do x more push-ups in a minute on the next day.

How many push-ups can he do in a minute on 11th days? (in term of x)

This looks just like a good-ol' fashioned arithmetic sequence with

a = 14 and d = x

use your formula for term(11)

It is the answer is 14 + 10x ?

correct

I hope x is small, to be realistic...

To find out how many push-ups Ali can do in a minute on the 11th day, let's break it down step by step.

We know that on the first day, Ali can do 14 push-ups in a minute. And on the next day, he plans to do x more push-ups in a minute.

So, on the second day, Ali can do 14 + x push-ups in a minute.

Now, let's see the pattern here. Each day, Ali is adding x push-ups to the previous day's number. This means that on the third day, he would do (14 + x) + x push-ups in a minute. On the fourth day, it would be ((14 + x) + x) + x push-ups, and so on.

We can see that the number of push-ups increases by x each day. So on the 11th day, Ali would do 14 push-ups (from the first day) plus 10 times x push-ups (since we need to add x push-ups for 10 days: 2nd-11th). This can be written as:

14 + 10x

So, Ali can do 14 + 10x push-ups in a minute on the 11th day.