Question

write 15c4 + 15c5 as a combined ncr (no value to be found)​

Answer 1

Given :  ¹⁵C₄ + ¹⁵C₅

To Find : Combined    ${^n}Cr$

Solution:

${^n}Cr=\frac{n!}{r!(n-r)!}$  

¹⁵C₄ + ¹⁵C₅

¹⁵C₄ = 15!/4!.11!

¹⁵C₅ = 15!/5!10!

¹⁵C₄ + ¹⁵C₅   = (15!/4!.11!)  + (15!/5!10!)

11! = 11.10!

5! = 5.4!

Takin LCM 11!.5!

=  ( 5. 15!  + 11.15!)/(11!.5!)

=  (5 + 11)  15! / (11!.5!)

= 16.  15! / (11!.5!)

16.  15! = 16 !

= 16!/(11!.5!)

= ¹⁶C₅

¹⁵C₄ + ¹⁵C₅  = ¹⁶C₅

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Answer 2

Answer:

Given :  ¹⁵C₄ + ¹⁵C₅

To Find : Combined    

Solution:

 

¹⁵C₄ + ¹⁵C₅

¹⁵C₄ = 15!/4!.11!

¹⁵C₅ = 15!/5!10!

¹⁵C₄ + ¹⁵C₅   = (15!/4!.11!)  + (15!/5!10!)

11! = 11.10!

5! = 5.4!

Takin LCM 11!.5!

=  ( 5. 15!  + 11.15!)/(11!.5!)

=  (5 + 11)  15! / (11!.5!)

= 16.  15! / (11!.5!)

16.  15! = 16 !

= 16!/(11!.5!)

= ¹⁶C₅

¹⁵C₄ + ¹⁵C₅  = ¹⁶C₅

Learn More:

7pr=60×7Pr-3=60 find r plz help me - Brainly.in

brainly.in/question/11779561

If 12cr is equal to 495 find the possible values of r - Brainly.in

brainly.in/question/13138388

If nPr=1680 and nCr=70. find n and r.

brainly.in/question/9116366

If nPr=840, nCr=35,find n.  

brainly.in/question/1700986

If npr = 3024 and ncr = 24 , then find r = Its a question from ...

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Step-by-step explanation: