Question

In an A.P the first term is 25 and the last term is -17 and the sum of n terms is 132.Find n and the common difference.
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Answer 1

Answer is in the above given attachment

Answer 2

Step-by-step explanation:

The formula is

Sn= (1st term + Last term/ 2) × n

132= 25+(-17)/2 × n

132= 25-17/2 × n

132= 8/2 × n

132= 4n

So n=132÷4

= 33

To find common difference d=

tn=a+(n-1)d [according to the formula]

-17=25+(33-1)d

-17=25+32d

-17-25=32d

-42=32d

-42/32=d

-21/16=d