Question

The sum of first four terms in AP is 36. and the product of first and fourth term is 45. find first four terms
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Answer 1

Answer:

t1+t2+t3+t4=36

let the 4 terms be

a-2d, a-d, a+d, a+2d

thus , a-2d+a-d+a+d+a+2d=36

4a=36

a=9

(a-2d)×(a+2d)=45

a²+2ad-2ad-4d²=45

a²-4d²=45

9²-4d²=45

4d²=81-45

d²=36/4

d²=9

d=3

thus the 4 terms are

a-2d,a-d,a+d,a+2d

putting values of a and d ,we get

3,6,12,15