6. On the world environment day tree plantation programme was arranged on a
which is triangular in shape. Trees are planted such that in the first row ther
one tree, in the second row there are two trees, in the third row three trees and
on. Find the total number of trees in the 25 rows.
Answers
Answered by
4
Answer:
total no of trees in 25th row is 325
Attachments:
Answered by
6
Answer:
325
Step-by-step explanation:
AP is 1,2,3,....
a=1 d=1 n = 25
Sn=n/2{2a+(n-1)d}
S25=25/2/{2+(25-1)1}
=25/2{2+24}
=25/2 ×26
=25×13
=325
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