Question

A.P 15,20,25, ka 115 kon sa padh hai?

Answer 1

a= 15 d=20-15 =5 , an= 115
an =a+(n-1)d , 115=15+(n-1)5 solve value

Answer 2

Answer:

T21 = 115

Step-by-step explanation:

$Tn = a + (n - 1)d \\ 115 = 15 + (n - 1)5 \\ 115 = 15 + 5n - 5 \\ 115 = 5n + 10 \\ 115 - 10 = 5n \\ \frac{105}{5} = n \\ 21 = n$