Question

Consider an A. P whose nth term is 2n+1.
find the sum of first ten terms.

Answer 1

Given nth term of an AP is 2n + 1.

Substitute n = 1, we get

= > 2(1) + 1

= > 3.

we know that sum of n terms = n/2(a + l)

= n/2(3 + 2n + 1)

= n/2(2n + 4).

Sum of first tern terms = 10/2(2(10) + 4)

= 5(20 + 4)

= 5(24)

= 120.

Therefore, the sum of first tern terms = 120.

Hope this helps!