Question

The sum of 15 terms of an arithmetic sequence with common difference 6 is 780.write the algebric expression of the sequence
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Answer 1

Answer:

Sn=n/2[2a+(n-1)d]

780=15/2[2a+14.6]

1560=30a+1260

300=30a

∴a=10

In order to find the algebraic expression we need to write 'an' term of an A.P,

an=a+(n-1)d

an=10+(n-1)6

Now replace 'an' with x and 'n' with y,we will get

x=10+6y-6

x=4+6y

⇒x-6y-4=0 is the required algebraic expression.

Hope it helps you.

Answer 2

Answer:

Step-by-step explanation: