Question

which
term
7
A.P 3,8,13,18....
is 78.​

Answer 1

Answer:

a1=3

CD=a2-a1 (CD= comman different)

CD=8-3 =5

an=a+(n-1)d

put the value

an=3+(7-1)5

an=3+6*5

an=3+30

an=33

so the 7th term is =33

Answer 2

Answer:

16th term of the A.P. will be 78

Step-by-step explanation:

Let tn = 78

Given: 3, 8, 13, 18, .. is an A.P.

a = 3, d = 8 - 3 = 5

tn = a + (n-1) d

78 = 3 + (n-1) 5

78 = 3 + 5n - 5

78 = 3 - 5 + 5n

78 = -2 + 5n

5n = 78 + 2

5n = 80

n = 80/5

n = 16