Question

Va rog frumos sa ma ajutați cu aceasta problema​

Answer 1

Răspuns: 0

Explicație pas cu pas:

$\frac{7!}{5!*2!} -\frac{6!}{5!*1!} -\frac{6!}{4!*2!} =\frac{6*7}{1*2} -6-\frac{5*6}{1*2} =21-6-15=0$

Answer 2

$\it C^5_7-C^5_6-C^4_6= \dfrac{7!}{5!\cdot2!}-\dfrac{6!}{5!\cdot1!}-\dfrac{6!}{4!\cdot2!}= \dfrac{5!\cdot6\cdot7}{5!\cdot2!}-\dfrac{5!\cdot6}{5!}-\dfrac{4!\cdot5\cdot6}{4!\cdot2!}=\\ \\ \\ = \dfrac{42}{2}-6-\dfrac{30}{2}=6-6=0$