Question

How many terms of the A.P. 55, 51, 47, ............. must be taken so that their sum is 405

Answer 1

Answer:

The general term of an AP is a + ( n- 1 ) d

Step-by-step explanation:

an = a + ( n - 1 ) d

405 = 55 + ( n- 1 ) -4

405 - 55 = ( n - 1 ) - 4

350 = ( n - 1 ) - 4

350/ - 4 = n - 1

- 87.5 = n - 1

-87.5 + 1 = n

-86.5 = n

So , Your answer is -86.5 terms .