Question

For the A.P given by a1,a2,....,an,....,with non zero common difference, the equation satisfied are A)a1+2a2+a3=0 D) a1-4a2+6a3-4a4+a5 B)a1-a2+a3=0 (one than more correct options) C)a1+3a2- 3a3 -a4=0

Answer 1

Sum of first n terms of AP, Sn = 2n2 + 5n

Now choose n =1 and put in the above formula,
First term = 2+5 = 7

Now put n=2 to get the sum of first two terms = 2x4 + 5x 2= 8 + 10 = 18

This means

first term + second term = 18

but first term =7 as calculated above

so, second term = 18-7 = 11

So common difference becomes, 11-7 = 4

So the AP becomes, 7, 11, 15, ....
nth term = a + (n - 1)d = 7 + (n-1)4 = 7 + 4n - 4 = 3 + 4и

Answer 2

Answer:

Sum of first n terms of AP, Sn = 2n2 + 5n

Now choose n =1 and put in the above formula,

First term = 2+5 = 7

Now put n=2 to get the sum of first two terms = 2x4 + 5x 2= 8 + 10 = 18

This means

first term + second term = 18

but first term =7 as calculated above

so, second term = 18-7 = 11

So common difference becomes, 11-7 = 4

So the AP becomes, 7, 11, 15, ....

nth term = a + (n - 1)d = 7 + (n-1)4 = 7 + 4n - 4 = 3 + 4и

Step-by-step explanation: