Question

Find the value of n, if the nth term of series 2,7,12.....and 74,71,68......are equal.

Answer 1

hey mate here is your answer ✌♥✌

an=an'

a+(n-1)d=a'+(n-1)d'

2+(n-1)5=74+(n-1)-3

2+5n-5=74-3n+3

8n=74+3+5-2

8n=80

n=10

hope it will help you

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Answer 2

Answer:

10

Step-by-step explanation:

(i) First AP:

Given, Series is 2,7,12...

Here, First term is 2.

Common difference = 5.

We know that nth term of an AP a(n) = a + (n - 1) * d

                                                             = 2 + (n - 1) * 5

                                                             = 2 + 5n - 5

                                                             = 5n - 3.

(ii) Second AP:

Given, Series is 74,71,68..

Here,

First term = a = 74.

Common difference = d = 71 - 74 = -3.

We know that nth term of an AP a(n) = a + (n - 1) * d

                                                             = 74 + (n - 1) * (-3)

                                                             = 74 - 3n + 3

                                                             = 77 - 3n

Now,

Given that (i) = (ii)

⇒ 5n - 3 = 77 - 3n

⇒ 8n = 80

⇒ n = 10.

Therefore, the value of n = 10.

Hope it helps!