Question

the 5th term of an aritamatic sequence 38and the 9th term is 66 what is its first term and the 15th term​

Answer 1

Answer:

HOPE IT HELPS YOU

Step-by-step explanation:

5th term= a+4d

Or 38=a+4d -equation 1

9th term=a+8d

Or 66=a+8d -equation 2

Eq.1-eq2

Or a+4d=38

a+8d=66

- - -

Or -4d= -28

Or d=28/4

d=7

Putting value of d in equation 1

a+4d=38

Or a+28=38

Or a=38-28

Or a=10

Now 25th term

25th term = a+24d

Or 10+24*7

Or 25th term=10+168

Or 25th term=178

Answer 2

The first term is 10 and the 15th term is 138

Step-by-step explanation:

5th term-38

9th term-66

15th term =?

An=a+(n-1)xd

38=a+(5-1)xd

38=a+4d -----(1)

An=a+(n-1)xd

66=a+(9-1)xd

66=a+8d-----(2)

solving both the equations:-

a+4d=38

a+8d=66

- - -

-4d=-28

4d=28

d = 28/4

d=7

put d in (1) to find a

a = 10

put a =10 and d= 7 in

An=a+(n-1)d

you will get the answer as 1st term =10

15th term = 138