Question

given l=28, S=144, and there are total 9 terms then find a​

Answer 1

Answer:

S=n/2(a+l)

2S=n(a+l)

2*144=9(a+28)

288=9a+252

9a=288-252

9a=36

a=36/9

a=4

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Answer 2

Answer:

S=144 l=28 n=9

Sn=n/2(a+l)

9/2(a+28)=144

a+28=32

a=4