Question

Determine the sum of first 25 terms of their A.p whose second term is 7 and 7^th term is 27.​

Answer 1

Answer:

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Answer 2

Answer:

Step-by-step explanation:

Let second term be a2=a+d=7

7 term be a7=a+6d=27

Soloving a+d=7

a+6d=27

We get d=-4 and a=11

Using the formula Sn=n/2 {2a+(n-1)d}

Sn=25/2 (2×11+24 (-4))

Sn=25/2 (22-96)

Sn=25/2 (-74)

Sn=25×(-37)

Sn=-925