Question

Find the 25th term of the AP: 9, 17, 25​

Answer 1

Answer:

Here,

a 1 =9

a 2 =a 1

+d=17

9+d=17

d=8

We know that, the sum of n terms of an A.P. is,

Sn = 2n

{2a+(n−1)d}

According to the question,

636= 2n

{2(9)+(n−1)8}

1272=18n+8n 2 −8n

8n 2 +10n−1272=0

4n 2+5n−636=0

n=12,−13.25

Ignore the negative value.

n=12

Hence, 12 terms of the A.P. is required to give a sum of 636.

Step-by-step explanation:

hence answer is 12terms.

Answer 2

Answer:

The answer is ( 201 ).

Step-by-step explanation:

Here before I have written the answer but it isn't taking.