Advertisements
Advertisements
Question
Find the sum of first 20 terms of an A.P. whose first term is 3 and the last term is 57.
Advertisements
Solution
Here,
First term, a = 3
Last term, l = 57
n = 20
`S = n/2 (a + I)`
= `20/2 (3 + 57)`
= 10 × 60
= 600
RELATED QUESTIONS
Find the sum of the following APs.
0.6, 1.7, 2.8, …….., to 100 terms.
Find the sum 2 + 4 + 6 ... + 200
Find the sum of the following Aps:
9, 7, 5, 3 … to 14 terms
If the 9th term of an A.P. is zero then show that the 29th term is twice the 19th term?
If first term of an A.P. is a, second term is b and last term is c, then show that sum of all terms is \[\frac{\left( a + c \right) \left( b + c - 2a \right)}{2\left( b - a \right)}\].
Find out the sum of all natural numbers between 1 and 145 which are divisible by 4.
If the first term of an A.P. is a and nth term is b, then its common difference is
First four terms of the sequence an = 2n + 3 are ______.
If 7 times the seventh term of the AP is equal to 5 times the fifth term, then find the value of its 12th term.
The sum of 41 terms of an A.P. with middle term 40 is ______.
