Q. 2 E5.0( 1 Vote )

# Find the sums ind

Formula used.

Sn = [2a + (n–1)d]

d = an + 1–an

In the sum above A.P follows

Is 25, 21, 17, 13, ……, (–51)

In the following A.P

a = 25,

d = 21–25 = –4

As the last term is –51

an = a + (n–1)d

–51 = 25 + (n–1)(–4)

–51 = 25–4n + 4

4n = 80

n = = 20

Sn = [2a + (n–1)d]

= [2×25 + (20–1)(–4)]

= 10[50 + 19×(–4)]

= 10[50–76]

= –260

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos  Arithmetic Progression- Don't miss these Questions56 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation view all courses RELATED QUESTIONS :

Find the sum of aGujarat Board Mathematics

Find the sum of aGujarat Board Mathematics

The ratio of the Gujarat Board Mathematics

If Tn Gujarat Board Mathematics

If the sum of theGujarat Board Mathematics

Sum to first l, mGujarat Board Mathematics

Find the sum of aGujarat Board Mathematics

If Sn Gujarat Board Mathematics

How many terms ofGujarat Board Mathematics

The sum of first Gujarat Board Mathematics