Question

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 ​

Answer 1

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

Answer 2

Answer:

Sum of 25 terms =1400

Explanation:

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