Sum of first forteen term of an a.P is 1505 and its forst term is 10.Find its 25th term.
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a =10 d = ?
Sn = n/2[ 2a + (n -1)d]
S14 = 14/2 [ 2(10) + ( 14-1)d] = 1505
= 7 [ 20 +13d] = 1505
= 20+ 13d = 1505/7
= 20 + 13d = 215
= 13d = 215-20
= 13d = 195
= d = 195/13
= d = 15
a 25 = a + 24d
a 25 = 10 + 24(15)
a25 = 10 + 360
a25 = 370
here is the answer mate.
hope it helps you.
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Sn = n/2[ 2a + (n -1)d]
S14 = 14/2 [ 2(10) + ( 14-1)d] = 1505
= 7 [ 20 +13d] = 1505
= 20+ 13d = 1505/7
= 20 + 13d = 215
= 13d = 215-20
= 13d = 195
= d = 195/13
= d = 15
a 25 = a + 24d
a 25 = 10 + 24(15)
a25 = 10 + 360
a25 = 370
here is the answer mate.
hope it helps you.
please mark it as brainliest.
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