if the second term and the fourth term of an A.P are 12 and 20 respectively then find the sum of first 25 terms
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Answered by
16
Answer:
a+d=12......(1)
a+3d=20.....(2)
Subtracting equation (1) from (2)
a+3d-a-d=20-12
2d=8
d=4, so a= 12-4=8
Sum of first 25 terms
Sn=n/2[2a+(n-1)d]
=12.5(16+24*4)
=12.5(112)
=1400
Answered by
12
Answer:
Sum of 25 terms =1400
Explanation:
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