Question

Which term in the A.P 7,3, 1.................. is -73?

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Answer 1

First term, a = 7
Common difference, d=3-7

Let -73 be the nth term.
a+(n-1) = -73
7+(n-1) x -4 = -73
-4(n-1) = -73-7
= -80
n-1 = 20
$\Rightarrow$ n = 21