the 13th term of ap is 2times of 10th term and 3rd term is 6times its 6th term find sum of first three terms
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3
Answer:
13 term means a+ 12d ...(1) and 10 term means a+9d. ....(2)
from given condition a+12d=2×(a+9d)
a+12d=2a+18d
a-2a+12d-18d=0
-a -6d=0.....(3)
-a=6d
multipleying by 5
-5a=30d....(4)
from second condition
a+2d=6(a+5d)
a+2d=6a+30d
a-6a+2d-30d=0
-5a -28d=0
from 4
30d-28d=0
2d=0
d=0
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Answered by
0
Answer:
15d
Step-by-step explanation:
a+12d=2(a+9d)
a+12d=2a+18d
2a-a+18d-12d=0
a+6d=0
a=-6d
a+2d=6(a+5d)
a+2d=6a+30d
6a-a+30d-2d=0
5a=-28d
S3=3/2(2[-6d}+2d)
S3=3/2(10d)
S3=15d
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