Question

the 10th tearm of an arithmetic sequence is 20and 20th term is 10.what is its common defferent
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Answer 1

Step-by-step explanation:

10th term

=a+9d=20-----------------(1)

20th term

=a+19d=10--–-------------(2)

from equation 1 and 2

a+9d=20

a+9d=20a+19d=10. -------×(-1)

a+9d=20

a+9d=20-a-19d=-10

-10d=10

d=-1

Answer 2

Answer:

d=-1

Step-by-step explanation:

let first term is a and common difference is d

So T10=a+9d=20....(1)

T20=a+19d=10...........(2)

Subtracting (1) frm(2)

19d-9d=10-20

=10d=-10

d=-1