Question

if the nth term of the ap 1,4,9,14....is129 find the value of n.

Answer 1

given that a = -1 n d = 5 an =129
an= a+(n-1)d =129= -1 +( n -1)*5
129 =-1 +5n -5= 129=5n -6 =129+6=5n
n=135/5=27
the nth term of AP is 27

Answer 2

The value of n = 27

Given :

The nth term of the AP - 1 , 4 , 9 , 14 , . . . . is 129

To find :

The value of n

Concept :

If in an arithmetic progression

First term = a

Common difference = d

Then nth term of the AP

= a + ( n - 1 )d

Solution :

Step 1 of 3 :

Write down the given progression

Here the given arithmetic progression is

- 1 , 4 , 9 , 14 , . . . .

Step 2 of 3 :

Write down first term and common difference

First term = a = - 1

Common Difference = d = 4 - ( - 1 ) = 4 + 1 = 5

Step 3 of 3 :

Find the value of n

Here it is given that nth term of the AP = 129

Thus we get

a + ( n - 1 )d = 129

⇒ - 1 + ( n - 1 ) × 5 = 129

⇒ - 1 + 5n - 5 = 129

⇒ 5n - 6 = 129

⇒ 5n = 135

⇒ n = 135/5

⇒ n = 27

Hence the value of n = 27

Correct question : If nth term of the AP - 1 , 4 , 9 , 14 , . . . . is 129 then find the value of n

━━━━━━━━━━━━━━━━

Learn more from Brainly :-

$1.$ If for an A.P., S15= 147 and s14=123 find t 15

(A) 24 (B) 23 (C) 47 (D) 46

https://brainly.in/question/34324030

2. Insert there arithmetic means between -20 and 4

https://brainly.in/question/29887163