Question

What is the sum of the first 20 terms of an AP and
A) 40 (B) 200 (C) 400 (D) 800​

Answer 1

Answer:

c is the answer for 20th term

Answer 2

Answer:

First term of AP = 3

common difference = 2

sum of 20 terms.

first term = 3

common difference = 2

so, sum of 20 terms of AP is 440.

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Some important formulas : -

an = a+(n-1)d

sn = n/2(a+l)

sn = n/2 ×[2a + (n -1 ) d]

where,

sn = sum of terms

a = First term

d = common difference

n = number of terms.

l = last term

an = nth term