Question

in 10th std 5.2 15th sum what isthe answer

Answer 1

Answer:

For what value of n, are the nth terms of two AP’s: 63, 65, 67… and 3, 10, 17… equal?

Ans. Lets first consider AP 63, 65, 67…

First term = a = 63, Common difference = d = 65 – 63 = 2

Using formula , to find nth term of arithmetic progression,

an = 63 + (n − 1) (2)… (1)

Now, consider second AP 3, 10, 17…

First term = a = 3, Common difference = d = 10 – 3 = 7

Using formula , to find nth term of arithmetic progression,

an = 3 + (n − 1) (7)… (2)

According to the given condition:

(1) = (2)

⇒ 63 + (n − 1) (2) = 3 + (n − 1) (7)

⇒ 63 + 2n – 2 = 3 + 7n − 7

⇒ 65 = 5n⇒ n = 13

Therefore, 13th terms of both the AP’s are equal.

Step-by-step explanation:

hope it helps