Question

in an Ap t1=4,t9=20 ,find t15

Answer 1

t1=4

t9=20

tn=a+(n-1)d. where a is first term and d is the common difference

a=4

a+8d=20 OR d=2

Therefore t15=a+14d

t15=4+14*2

t15=32

Answer 2

Answer:

t1=4,t9=20 an=a+(n-1)d

Step-by-step explanation:

a=4 after applying formula we get a+8d=20 then substituite a value we get 4+8d=20,8d=20-4=16,8d=16,d=16/8,d=2. t15=a+(n-1)d,after substituiting values we get t15=4+(15-1)2,t15=4+14×2,4+28,=32