Question

3rd term of an A.P. exceeds the first term by 12. if the last term is 205 and the first is 25 .Find the number of terms of the A.P.​

Answer 1

Answer:

n = 31.

Explanation:

$a + 2d = a + 12 \\ \\ \\ 2d = 12 \\ \\ d = 6 \\ \\ a + (n - 1)d = 205 \\ \\ 25 + (n - 1)d = 205 \\ \\ (n - 1)d = 180 \\ \\ n - 1 = \frac{180}{6} \\ \\ n = 30 + 1 \\ \\ n = 31.$

Answer 2

31

• hence the number of terms of the given A.P. is 31