Question

The 4th and 10th term of an ap are 13 and 25 . Find its first term

Answer 1

Answer:

the answer is 7 as the first term of the AP is 7

Answer 2

Answer:

given.

t4=13 and t10=25

to find : t1.

solution.

we known that,

tn=a+(n-1)d

t4=a+(4-1)d

13=a+3d

a+3d=13.........................(1)

t10=a+(10-1)d

25=a+9d

a+9d=25.........................(2)

substracting equation (2 )and (1).

a+9d=25

a+3d=13

.................

6d=12

d=12/6

d=2

put the value of d=2 in equation (1)

a+3d=13

a+3*2=13

a+6=13

a=13-6

a=7

In arithmetic progression

t1=a

t1=7.

the value of first term is 7.