3. If the common difference of an AP is 3, then what is a18-a13

1 thought on “3. If the common difference of an AP is 3, then what is a18-a13”

1. Answer:

   Given, common difference of the AP,

   d=5

   We know that,

   a

   n

   =a

   1

   +(n−1)d

   Then,

   a

   18

   =a

   1

   +17×d

   a

   13

   =a

   1

   +12×d

   Solving the two equations,

   a

   18

   −a

   13

   =a

   1

   +17d−a

   1

   −12d

   a

   18

   −a

   13

   =5d,

   Substituting d=5,

   a

   18

   −a

   13= 25

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