if middle term of the AP is 49.find the sum of first 25 terms.
Answers
Answered by
3
Answer:
N13 = 49
A +( n-1 )= 25th term
a+12d=49
12d=49-a
d= 49-a÷12
solve it
Answered by
8
Answer:
1225
Step-by-step explanation:
The AP consists of 25 terms i.e. odd number of terms.
So, the middle term of the AP would be [(25+1)/2]th term = 13th term
The middle term is a₁₃.
Given, the middle term of the AP is 49.
⇒a₁₃=49
⇒a+12d=49 -------------------(i)
⇒Sum of the AP= n/2{2a+(n-1)d}
=25/2[2a+(25-1)d]
=25/2(2a+24d)
(Here take 2 as common)
=25/2 * 2(a+12d)
=25(a+12d)
(From (i), we got a+12d=49)
=25*49
=1225
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