what is the sum of thr first 20 terms of an AP if a = 4 and t20= 36 ? A) 40 B) 200 C) 400 D) 800`​

1 thought on “what is the sum of thr first 20 terms of an AP if a = 4 and t20= 36 ? A) 40 B) 200 C) 400 D) 800`​”

1. Step-by-step explanation:

   t20=4+19d=36

   19d=32

   d=32/19

   S20=10[8+19×32/19]

   =10[40]

   =400

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