Question

find the 15th term of the AP -5,1,7,13​

Answer 1

Answer:

a+14d

a= -5

d=1+5=6

-5+84=79

Answer 2

Given :

A.P. = -5 , 1 , 7 , 13

To find :

15th term of given A.P. that is,

$\sf T_{15}$

Formula used :

$\sf \: T_{n} \: = a \: + (n - 1)d$

Here,

• a = First term
• d = common difference
• Tn = nth term

Solution :

$\sf \: d \: = a_{2} - a_{1} \\ \\ \sf \implies \: d \: = 1 - ( - 5) \\ \\ \sf \implies \: d \: = 6$

therefore

$\sf \: T_{15} \: = ( - 5) + (15 - 1) \times 6 \\ \\ \sf \implies \: T_{15} \: = ( - 5) + (14 \times 6) \\ \\ \sf \implies \: T_{15} \: =( - 5) + 84 \\ \\ \sf \implies \: T_{15} \: =79$

ANSWER :

15th term of given AP = 79