Question

Sum of first 15 terms of an
arithmetic sequence is 300.

a) Find the 8th term?
b)If first term is 6,what
common difference?
c) Write the algebraic
expression?​

Answer 1

Answer:

Step-by-step explanation:

$Sum of 15 terms=\frac{15}{2}[2a +(15-1)d]\\ 300=\frac{15}{2}[2a+14d]\\ 300=\frac{15}{2}[2(a+7d)]\\ 300=15(a+7d)\\\frac{300}{15}=(a+7d)\\ 20= a+7d$

a+7d= 8th term

Therefore a)20

if a=6(first term)

6+7d=20

7d=14

d=2

Therefore Common Difference is 2

Algebraic expression= a +(n-1)2

If a=6

6+(n-1)2

6+2n-2

4+2n