Question

Consider the arithmetic sequence 4, 10, 16, .........

(a) What is its common difference ?

(b) Write is its 11th term.

(c) Calculate the sum of first 21 terms.

(d) find the sum of first 20 terms of the arithmetic sequence 10, 16, 22, .........​

Answer 1

Answer:

a. 6

b. a+10d = A11

4+10×6=64

c. s=n/2(2a+(n-1)d)d.

= 20/2 (2×4+19×6)

= 10×102

= 1020

d.s=n/2(2a+(n-1)d)

= 20/2(2×10+19×6)

= 10× 114

= 1140