Question

Calculati :5 C ²₄-A²₅

Answer 1

$C_{4}^{2} =\frac{4!}{2!*(4-2)!}=\frac{2!*3*4}{2!*1*2}=\frac{12}{2}=6$

$A_{5}^{2}=\frac{5!}{2!}=\frac{5!}{5-2!}=\frac{3!*4*5}{3!}=20$

5*6-20=30-20=10

Answer 2

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