Question

In an AP A2 = 14 A3=18 find S51​

Answer 1

A2 = 14

A3 = 18

Common Difference= A3 - A2

= 18 - 14

= 4

d = 4

Now

A2 = A+d = 14

A+4 = 14

A= 14-4

= 10

Now S51 ( Sum of 51 terms )

= {51 (2A + 50d)/2}

= {51 (20+ 200)/2}

= (51 × 220)/2

= 51× 110

= 5610

Therefore the value of S51 is 5610

Hope it Helped :)