If for an A.P, S15 = 225 and t15 = 20, then a =?
Answers
Answered by
1
Step-by-step explanation:
GIVEN :
S15 = 225
T15 = 20
TO FIND :
VALUE OF a.
SOLUTION :
SOLUTION IS EXPLAINED IN THE DIAGRAM.
ANSWER :
a = FIRST TERM IS 10.
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Answered by
0
Step-by-step explanation:
We know that the formula for the nth term is t
n
=a+(n−1)d, where a is the first term, d is the common difference.
It is given that the nth term is t
15
=55 and the first term is a=13, therefore,
t
n
=a+(n−1)d
⇒55=13+(15−1)d
⇒55=13+14d
⇒14d=55−13
⇒14d=42
⇒d=
14
42
=3
Hence, d=3
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