If $a_{1} = 1$ and $a_{n} = na_{n - 1}$ for all positive integer $n \geq 2,$ then $a_{5}$ is equal to

Question

Dr. Abubacker · Accepted Answer

(b)
Given, $a_{n} = na_{n - 1}$
For $n = 2$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ a_{2} = 2a_{1} = 2$ $(\because a_{1} = 1$given)
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ a_{3} = 3a_{2} = 3(2) = 6$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ a_{4} = 4\left( a_{3} \right) = 4(6) = 24$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ a_{5} = 5\left( a_{4} \right) = 5(24) = 120$

Q. If $a_{1} = 1$ and $a_{n} = na_{n - 1}$ for all positive integer $n \geq 2,$ then $a_{5}$ is equal to

Explanation

Reviewed by Dr. Abubacker

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