Question

In an arithmetic sequence u1=7, u20=64, un=3709 find the value of common difference and find the value of n?

Answer 1

Answer:

Step-by-step explanation:

u1=u=7

u20=u+19d

u+19d=64

7+19d=64

19d=64-7=57

d=57/19

d=3

Un=3709

Un=a+(n-1)d

3709=7+(n-1)3

3709-7=(n-1)3

3702=(n-1)3

(n-1)=3702/3

(n-1)=1234

n=1235