find the sum of the first 30 terms of an A.P whose first term is-2, and common difference is 3.
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the sum of the first 30 terms of an A.P whose first term is-2, and common difference is 3 is 1245
Step-by-step explanation:
a =-2 and d = 3
Sn = n/2[2a + (n-1)d]
S30 = 30/2[2(-2) + 29(3)]
= 15[ (-4) + 87]
= 15[83]
S30 = 1245
Answered by
4
Step-by-step explanation:
Given:-
An A.P whose first term is-2, and common difference is 3.
To find:-
Find the sum of the first 30 terms of the A.P ?
Solution:-
Given that :
First term of the AP (a) = -2
Common difference (d) = 3
Number of terms (n) = 30
We know that
The sum of first n terms in an AP = Sn
= (n/2) [2a+(n-1)d]
On Substituting these values in the above formula then
=> S 30 = (30/2)[2(-2)+(30-1)(3)]
=> S 30 = (15)[-4+29(3)]
=> S 30 = 15[-4+87]
=> S 30 = 15(83)
=> S 30 = 1245
Answer:-
The sum of first 30 terms in the given AP is 1245
Used formula:-
- The sum of first n terms in an AP = Sn
- = (n/2) [2a+(n-1)d]
- a = First term
- d = Common difference
- n = number of terms
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