Réitigh =12!/(18-5)!5!=12!/7!5!=

$$= \frac { 12 ! } { ( 18 - 5 ) ! 5 ! } = \frac { 12 ! } { 7 ! 5 ! } =$$

Fíoraigh

Céimeanna Réitigh

Is é iolrán 12 ná 479001600.

$$\frac{479001600}{\left(18-5\right)!\times 5!}=\frac{12!}{7!\times 5!}$$

Dealaigh 5 ó 18 chun 13 a fháil.

$$\frac{479001600}{13!\times 5!}=\frac{12!}{7!\times 5!}$$

Is é iolrán 13 ná 6227020800.

$$\frac{479001600}{6227020800\times 5!}=\frac{12!}{7!\times 5!}$$

Is é iolrán 5 ná 120.

$$\frac{479001600}{6227020800\times 120}=\frac{12!}{7!\times 5!}$$

Méadaigh 6227020800 agus 120 chun 747242496000 a fháil.

$$\frac{479001600}{747242496000}=\frac{12!}{7!\times 5!}$$

Laghdaigh an codán \frac{479001600}{747242496000} chuig na téarmaí is ísle trí 479001600 a bhaint agus a chealú.

$$\frac{1}{1560}=\frac{12!}{7!\times 5!}$$

Is é iolrán 12 ná 479001600.

$$\frac{1}{1560}=\frac{479001600}{7!\times 5!}$$

Is é iolrán 7 ná 5040.

$$\frac{1}{1560}=\frac{479001600}{5040\times 5!}$$

Is é iolrán 5 ná 120.

$$\frac{1}{1560}=\frac{479001600}{5040\times 120}$$

Méadaigh 5040 agus 120 chun 604800 a fháil.

$$\frac{1}{1560}=\frac{479001600}{604800}$$

Roinn 479001600 faoi 604800 chun 792 a fháil.

$$\frac{1}{1560}=792$$

Coinbhéartaigh 792 i gcodán \frac{1235520}{1560}.

$$\frac{1}{1560}=\frac{1235520}{1560}$$

Cuir \frac{1}{1560} agus \frac{1235520}{1560} i gcomparáid lena chéile.

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