Question

Sum of first 10 terms of an arithmetic sequence is 350. Sum of first 15 terms is 750 Find 8th term of the sequence Find sum of 3rd term and 10th term Find first term and common difference



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Answer 1

Answer:

We know Sn=(n/2)*(2a+(n-1)d)

Where n is the number of terms

d is the common difference

a is the first number

Substiothe given values

S15=750

n=15

a=15

Using above equation

750=(15/2)*[2*15+(15–1)d]

[(750*2)/15]=30+14d

100=30+14d

70=14d

This yields d as 5

Then substitute for 20th Term using

Tn = a+(n-1)d

T20=15+(20–1)5

T20=15+(19*5)

T20=15+95

T20=110

Hope you got the answer

Answer 2

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