Question

sum of 20 term of ap whose 2nd and3rd term is 14 and 18 respectively ​

Answer 1

a+d=14

a+2d=18

So,d=4

And a:

a+4=14

a=10

S20=20/2[2(10)+19(4)]

10[20+76]

10[96]

960

HOPE this helps you...