Question

The term  A.P is 8, 10, 12, 14,...., 126 . find A.P.

Answer 1

The given A.P is 8, 10, 12, 14,...., 126.
a = 8 and d = 2.
When this A.P is reversed, we get the A.P.
126, 124, 122, 120,....
So, first term becomes 126 and common difference −2.
The sum of first 10 terms of this A.P is as follows: 

\[S_{10} = \frac{10}{2}\left[ 2 \times 126 + 9\left( - 2 \right) \right]\]

\[ = 5\left[ 234 \right]\]

\[ = 1170\]