Respuesta :

Formula for permutation is:

[tex] \boxed{ \tt^{n} C_{r} = \frac{n!}{r!(n - r)!} }[/tex]

Calculation,

Plug in the values:

Required number of ways = ²C7

  • n = 7
  • r = 5

[tex] \sf \frac{7!}{5!(7 - 5)!} [/tex]

[tex] \sf \frac{7 \times 6 \times \cancel{5!}}{ \cancel{5! }\times 2!} [/tex]

[tex] \sf \frac{7 \times 6 }{ 2!} [/tex]

[tex] \sf \frac{42 }{ 2!} [/tex]

[tex] \sf \frac{42 }{ 2} = 21[/tex]

Thus, The players can be selected in 21 different ways!!~

Here one player cannot be repeated so repeating is not allowed.

  • Hence we use combination here

  • n=7
  • r=5

Total ways

[tex]\\ \rm\hookrightarrow ^nC_r=\dfrac{n!}{r!(n-r)!}[/tex]

  • Put values

[tex]\\ \rm\hookrightarrow ^7C_5[/tex]

[tex]\\ \rm\hookrightarrow \dfrac{7!}{5!(7-5)!}[/tex]

[tex]\\ \rm\hookrightarrow \dfrac{7!}{5!2!}[/tex]

[tex]\\ \rm\hookrightarrow \dfrac{7\times 6\times 5!}{5!(2)}[/tex]

[tex]\\ \rm\hookrightarrow \dfrac{7(6)}{2}[/tex]

[tex]\\ \rm\hookrightarrow \dfrac{42}{2}[/tex]

[tex]\\ \rm\hookrightarrow 21ways[/tex]

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