1.

Find the sum of first 30 term of an ap 1.5.9.13​

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Answer:

ANSWER

Let a be the first term d be the common difference of the GIVEN A.P.

Then, a

2

=2 and a

7

=22

⟹a+d=2 ............ (1)

and a+6d=22 .............. (2)

Solving these two EQUATION, we get a=−2 and d=4.

∴S

30

=

2

30

{2×(−2)+(30−1)×4} ....[Puttingn=30,a=−2 andd=4inS

n

=

2

n

{2a+(n−1)d}]

⟹S

30

=15(−4+116)=15×112=1680

Hence, the sum of first 30 TERMS is 1680.

PLS THANKS MY ANSWER



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