Question

Объясните....... .......​

Answer 1

$\frac{P_{6}-P_{4}}{P_{5}}=\frac{6!-4!}{5!}=\frac{6*5*4*3*2*1*-4*3*2*1}{5*4*3*2*1*}=\frac{4*3*2*1(6*5-1)}{5*4*3*2*1}=\frac{29}{5}=5,8\\\\\frac{A_{8}^{4} -A_{8}^{3}}{A_{7}^{3}-A_{7}^{2}}=\frac{\frac{8!}{(8-4)!}-\frac{8!}{(8-3)!}  }{\frac{7!}{(7-3)!} -\frac{7!}{(7-2)!}} =\frac{\frac{4!*5*6*7*8*}{41}-\frac{5!*6*7*8}{5!}}{\frac{4!*5*6*7}{4!}-\frac{5!*6*7}{5!}}=\frac{6*7*8(5-1)}{6*7(5-1)}=8$

$\frac{C_{6}^{3}-C_{6}^{2}}{A_{6}^{2}}=\frac{\frac{6!}{3!*3!}-\frac{6!}{2!*4!}}{\frac{6!}{4!}}=\frac{\frac{4*5*6}{1*2*3}-\frac{5*6}{1*2}}{5*6}=\frac{20-15}{30}=\frac{5}{30}=\frac{1}{6}$