Question

Find the sum of first 51 terms of an AP whose second and third terms are 14 and 18 respectively.​

Answer 1

Step-by-step explanation:

a+d=14------(1)

a+2d=18------(2)

equation (1)-(2)

-d=-4 ya d=4

put d=4in equation (1)

a+4=14

a=14-4

a=10

Sn=51/2[ 2a+(n-1)d]

=51/2[2×10+(51-1)4]

=51/2[20+200]

=51/2×220

=51×110=5610

Answer 2

Refers to attachment ♡~