Question

The sum of first n terms of an A.P with first term a and nth term l will be​

Answer 1

Given:

First term of A.P is a

nth term =I

Let d be the common difference

nth term=a+(n-1)d d-l-a/n-1---- -1

I=a+(n-1)d

Mth term from the beginning =a+(m-1)d=a+(m-1)(l-a/n-1) ·

Mth term from the end we get: where we consider first term as I and the common difference=-d =l-(m-1)(l-a)/n-1 -3

=l+(m-1)(-d)

=l+(m-1)x(-(l-a)/n-1)

thus sum of mth term from beginning to

end is =a+(m-1)(l-a/n-1 ) +1-(m-1)(l-a)/n-1

=a+l

Hence proved

Answer 2

Answer:

Step-by-step explanation:

we have an equation for finding the sum of first n terms of an ap

Sⁿ=n/2(2a+(n-1)d) or Sⁿ=n/2(a+l)

where Sⁿ is the sum of n terms

n is the number of terms

a is the first term

l is the last term

d is the common difference

hope this helps you

thank you