Question

IF a 3 and to - 27, find the Sum of the first six des cas of the A. P​

Answer 1

Answer:

-387

Step-by-step explanation:

As we know,

first term of the AP is represented by a which is given 3 in this question and common difference is represented by d which is -27

Then

As we know

sum of n digits of an AP is =

$\frac{n}{2} (2a \: + (n - 1)d)$

inserting the valves of n , a and d we get the sum of first six digits of the AP

=>

$\frac{6}{2} ((2 \times 3) \: + (6 - 1)( - 27))$

$= > \: 3 \times (6 + ((5) \times ( - 27)))$

$= > \: 3 \times (6 + ( - 135))$

$= > \: 3 \times ( - 129)$

$= > - 387$

Hence sum of first six digits of the given AP is -387