Question

For ap t4=20and t15=64 find tn.​

Answer 1

Answer:

- 1

Step-by-step explanation:

T4 = 20

a + 3d = 20 ------- (1)

T15 = 64

a + 14d = 64 ------- (2)

solving (1) and (2) we get,

a = 8

d = 4

so,

Tn = a + (n - 1 ) * d

Tn = 8 + (n - 1 ) * 4

Tn = 8 + 4n - 4

4n = -4

n = -1