Question

The sum of 10th and 11th term of an arithmetic sequence is 65.

a.what is the sum of it's first and 20th term
b.what is the sum of first 20 terms of this sequence?
c.if the 4th term of this sequence is 13, what is it's 17th term?
d.what is the common difference of this sequence? ​

Answer 1

Step-by-step explanation:

a. 65

b. 650

c. 52

d. 3

it is the answer to your questions

Answer 2

Other wise we can do second answer as

$\frac{20}{2} (x1 + x20) = 10 \times 65 = 650$