Question

the sum of first n terms of an ap is given by n^2+8n.find and d and also find the sum of the terms of 50 terms​

Answer 1

Step-by-step explanation:

If n=1, then:

S1=a=> (1)²+8×1

=> 1+8=9.

If n=2, then:

S2=> (2)²+8×2

=> 4+16=20.

A2=S2-S1=> 20-9=11.

d=a2-a=11-9=3.

If n=50, then:

S50=> (50)²+8×50

=> 2500+400

=> 2900.