Question

determine a expressão correspondente a: Ax,2

Answer 1

$A_{x,2}= \dfrac{x!}{(x-2)}= \dfrac{x\cdot(x-1)\cdot(x-2)!}{(x-2)!}=x(x-1)$

Answer 2

X!

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(X-2)!

X.(X-1).(X-2)

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(X-2)!

X.(X-1)

= X²-X