what is the sum of the first 20 terms of an Ap if a = 4 and t20=36? Please answer I will mark you brainliest..plzzz
Answers
Answered by
11
Answer:
Given,
a= 4
20th term or last term for finding sum = 36
number of term = 20
Sum of n term =
(a + l) \times n \div 2(a+l)×n÷2
where
a= first term = 4
l = last term = 36
and n = no. of terms = 20
After substituting value
Sum = (4 + 36)X 20/2
= 40 X 10
= 400
aloksatishchandrasha:
actually I want this in a simple way
ohhh
ok
I know this way only
ok
but plz mark me as a brainlist plzz
which formula is used here
it is there in arithmetic progression
Answered by
6
Step-by-step explanation:
Given,
a= 4
20th term or last term for finding sum = 36
number of term = 20
Sum of n term =
(a + l) \times n \div 2(a+l)×n÷2
where
a= first term = 4
l = last term = 36
and n = no. of terms = 20
After substituting value
Sum = (4 + 36)X 20/2
= 40 X 10
= 400
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