Question

What is the sum of the first 20 terms of an A.P, if a =4 and t20=36?​

Answer 1

Answer:

400

Step-by-step explanation:

Here a ( n ) = a + ( n - 1 ) d = last term = a ( 20 ) Sum = 20/2 ( 4 + 36 ) = 10 ( 40 ) = 400. Sum of the first 20 terms is 400