Răspuns:
b. x = 10; c. x = 7
Explicație pas cu pas:
b.
[tex]\frac{x!}{(x - 4)!}+\frac{x!}{(x - 3)!} = 10 (x - 2) \times \frac{(x - 1)!}{(x - 1- 2)!} \\ \frac{(x - 3 + 1) \times x!}{(x - 3)!} = \frac{10(x - 2)(x - 1)!}{(x - 3)!} \\ (x - 2)x! = 10(x - 2)(x - 1)! \\ x(x - 1)! = 10(x - 1)! \\ x = 10[/tex]
c.
[tex]x! + \frac{x!}{(x - x + 1)!} = 14 \times (x - 1)! \\ x! + x! = 14(x - 1)! \\ 2x(x - 1)x! = 14(x - 1)! \\ x = 7[/tex]
