Question

If nC9 = nC8 find nC15

Answer 1

$\underline{\boxed{\bold{Question}}}$

• $If \;^nC_{9} = ^nC_{8} , then\; find\; ^nC_{15}$

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$\underline{\boxed{\bold{Important \; formula\;to\;be\;remembered}}}$

↬  $\frac{^nC_{r}}{^nC_{r-1}} = \frac{n-r+1}{r}$

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$\underline{\boxed{\bold{Answer}}}$

Let's Start !

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$:\implies \;^nC_{9} = ^nC_{8}$

$:\implies\frac{^nC_{9}}{^nC_{8}} = 1$

$:\implies\frac{^nC_{9}}{^nC_{9-1}} = \frac{n-9+1}{9} = 1$

$:\implies \frac{n-9+1}{9} = 1$

$:\implies {n-9+1} = 9$

$:\implies n = 9 + 9 -1 = 17$

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$\underline{\boxed{\bold{\therefore Value \;of\;n=17}}}$

$\underline{\boxed{\bold{^nC_{15} = ^{17}C_{15} =136 }}}$

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Hope this helps u.../

【Brainly Advisor】

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Answer 2

Answer:

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