Question

find the sum of first 10 terms of the arithmetic sequence 7, 13, 29, - - - - - - - ​

Answer 1

Answer:

Let me try to answer this without using complex math equations.

The sequence is 7, 10, 13, 16, 19, … which means each term increases by 3.

Let’s first find the last (30th) term. Since each time, it gets increased by 3, by the 30th term, it would have been increased 29 times compared to the first one. Right?

So, the 30th item equals 7 + 3 * 29 = 94.

Now, if we add 7 (1st term) to the 30th term, that sum is equal to 10 (2nd term) + 29th item, because 10 is larger than 7 by 3, and 29th term is smaller than the 30th item by 3.

So, 7 + 94 = 101.

The final answer: 101 * 15 (because there are 30 terms in total and we’re getting 101’s by taking 2 terms each time) = 1515.