Question

Find first term of  AP ,l(last term) = 28, S = 144, and there are total 9 terms.​

Answer 1

Answer:

Sum = n/2 ( a + l )

144 = 9/2 ( a + 28 )

288 = 9 ( a + 28 )

32 = a + 28

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