Question

which term of ap 3,8,13,18 is 78

Answer 1

Answer:

16th term in given A.P is 78

Step-by-step explanation:

Given A.P : 3,8,13,18,....,78

First term (a) = 3 ,

common difference (d)= $a_{3}-a_{2}$

= $8-3$

= $5$

$Let \:n^{th} \: term = 78$

$\implies a+(n-1)d=78$

$\implies 3+(n-1)\times 5 = 78$

$\implies (n-1)\times 5 = 78-3$

$\implies (n-1)\times 5 = 75$

$\implies n-1= \frac{75}{5}$

$\implies n-1=15$

$\implies n=15+1$

$\implies n=16$

Therefore,

16th term in given A.P is 78

••••

Answer 2

Answer:

The givenA.P.3,8,13,18,......78

Step-by-step explanation:

a=3

d=a2-a1=8-3=5

nth term of the A.P. be 75

WKT :

an=a+(n-1)d

78 = 3+(n-1)×5

75-3=(n - 1) ×5

75 =5 (n-1)

5(n-1) = 75

(n-1)=75/5

(n-1)=15

n=15+1

n=16

I HOPE THIS WILL HELP YOU ^_^