10 th question the middle term value is 551 sum of both sides of middle term is20704 and49824
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nehasharma5700:
is that keaves a remainder 5 when divided by 7
??
Ya
When a 3 digit no. Suppose 999 divided by 7 leaves remainder 5 nd we have to find middle term
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103,110,117.......999
an=a+(n-1)d
999=103+(n-1)7
999-103=(n-1)7
896/7=n-1
128+1=n
129=n this is odd then (129+1)/2
=130/2=65th term
a65=103+64(7)
=103+448
=551
S64=64/2(2(103)+63(7) )
=32(206+441)
=32(647)
=20704
S129=129/2(206+128(7))
=129/2(206+896)
=129/2(1102)
=71079
S129-(S64+551)
71079-(20704+551)
71079-21255
49824
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