Find the A.P. whose nth term is 7 – 3K. Also find the 20th term. - Vidyadip

Question

Find the $A.P$. whose nth term is $7 – 3K$. Also find the 20th term.

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Answer

$T_n = 7 – 3n$
Giving values $1, 2, 3, 4, …$ to n, we get
$T_1 = 7 – 3 x 1 = 7 – 3 = 4$
$T_2 = 7 – 3 x 2 = 7 – 6 = 1$
$T_3 = 7 – 3 x 3 = 7 – 9 = -2$
$T_4 = 7 – 3 x 4 = 7 – 12 = -5$
$T_{20} = 7 – 3 x 20 = 7 – 60 = -53$
$A.P$. is $4, 1, -2, -5, …$
$20$th term $= -53$

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