Math, asked by mairawajahat, 10 months ago

In an arithmetic progression the ninth term is 18 and the sum of the first nine terms is 72. Find the common difference and the first term.

Answers

Answered by yajat1810

8

a+8d = 18. (1)

9/2(2a+8d) = 72

a+4d = 8. (2)

(1)-(2)

4d = 10

d = 5/2

a = -2

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