1) [latex] C^{2} _{x-1} = 6[/latex]2) [latex] A^{3} _{x+2} = 6x(x+1)[/latex]3)[latex] \frac{A_{x} ^{4} * P_{x-4}}{ P_{x-2} } [/latex] = 42

Question

1) [latex] C^{2} _{x-1} = 6[/latex]2) [latex] A^{3} _{x+2} = 6x(x+1)[/latex]3)[latex] \frac{A_{x} ^{4} * P_{x-4}}{ P_{x-2} } [/latex] = 42

1) [latex] C^{2} _{x-1} = 6[/latex] 2) [latex] A^{3} _{x+2} = 6x(x+1)[/latex] 3)[latex] \frac{A_{x} ^{4} * P_{x-4}}{ P_{x-2} } [/latex] = 42

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Ответ(ы) на вопрос:

Accepted Answer

[latex]1)\;C_{x-1}^2=6\\\frac{(x-1)!}{2!(x-1-2)!}=6\\\frac{(x-1)!}{2!(x-3)!}=6\\\frac{(x-2)(x-1)}{2!}=6\\x^2-3x+2=12\\x^2-3x-10=0\\D=9+4\cdot10=49\\x_1=-2,\;x_2=5\\2)\;A_{x+2}^2=6x(x+1)\\\frac{(x+2)!}{(x+2-2)!}=6x(x+1)\\\frac{(x+2)!}{x!}=6x(x+1)\\\frac{(x+1)(x+2)}{x}=6x(x+1)\\\frac{(x+2)}{x}=6x\\x+2=6x^2\\6x^2-x-2=0\\D=1+4\cdot6\cdot2=49\\x_1=-\frac12,\;x_2=\frac23[/latex] [latex]3.\;\frac{A_x^4\cdot P_{x-4}}{P_{x-2}}=42\\\frac{\frac{x!}{(x-4)!}\cdot(x-4)!}{(x-2)^!}=42\\\frac{x}{(x-2)!}=42\\(x-1)x=42\\x^2-x-42=0\\D=1+4\cdot42=169\\x_1=-6,\;x_2=7[/latex]