Look at these triangles made with dots. How many dots are there in each. Arithmetic sequence

 2) Look at these triangles made with dots. How many dots are there in each?

Compute the no.of dots needed to make the next three triangles





Ans:
  3,6,10

   3+3=6
   6+4=10
  10+5=15

       The no of dots needed to make the next three triangles will be:
  

   10+5  =15
   15+6  =21
   21+7  =28
  

15,21,27 dots
 

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