the sum of first 13 terms of arithmetic sequence is 299 and next 12 terms is 726 find d?
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Answer:3
Step-by-step explanation:
s13=299
13/2*(2a+12d)=299
2a+12d=(299*2)/13
2a+12d=46
a+6d=23
s25=1025
25/2*(2a+24d)=1025
2a+24d=(1025*2)/25
2a+24d=82
a+12d=41
from the above 2 equations
6d=18
d=3
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