Math, asked by gone2, 1 year ago

nc2 = 45 find n (it's from combinations)

Answers

Answered by xyz99
25
ur answer is n=10
hope
... it help u
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Answered by pulakmath007
1

The value of n = 10

Given :

\displaystyle \sf{  {}^{n}C_2 = 45  }

To find :

Find the value of n

Solution :

Step 1 of 2 :

Write down the given equation

Here the given equation is

\displaystyle \sf{  {}^{n}C_2 = 45  }

Step 2 of 2 :

Find the value of n

\displaystyle \sf{  {}^{n}C_2 = 45  }

\displaystyle \sf{ \implies {}^{n}C_2 = 5 \times 9}

\displaystyle \sf{ \implies {}^{n}C_2 =  \frac{10 \times 9}{2} }

\displaystyle \sf{ \implies {}^{n}C_2 =  \frac{10 \times 9 \times 8!}{8! \times 2!} }

\displaystyle \sf{ \implies {}^{n}C_2 =  \frac{10 !}{8! \times 2!} }

\displaystyle \sf{ \implies {}^{n}C_2 =  \frac{10 !}{2! \times 8!} }

\displaystyle \sf{ \implies {}^{n}C_2 =  \frac{10 !}{2! \times (10 - 2)!} }

\displaystyle \sf{ \implies {}^{n}C_2 =  {}^{10}C_2  }

\displaystyle \sf{ \implies n = 10 }

Hence the required value of n = 10

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