Question

for what value of n are the nth term of the following APs are equal? 1. 1,7,13,....​

Answer 1

Answer:

Given,

a

1

=13

d

1

=19−13=6

T

1

(n)=13+(n−1)6........(1)

a

2

=69

d

2

=68−69=−1

T

2

(n)=69+(n−1)(−1)........(2)

equating (1) and (2), we get,

13+(n−1)6=69+(n−1)(−1)

7n=70−7=63

∴n=9

T

1

(9)=13+(9−1)6=61...........A

T

2

(9)=69+(9−1)(−1)=61........B

both the values of A and B are same.