Question

if npr =5040and ncr= 210 then find n,r
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Answer 1

Answer:

Npr=5040 and NcR=210

Step-by-step explanation:

Npr=n!÷(n-r)!

NcR=n!÷r!(n-r)!

We have,  nPr=5040 and nCr=210,

(n−r)!n!=5040 and (n−r)!r!n!=210

Divide both 

r!=24⇒r=4

So (n−4)!n!=5040

⇒(n−4)!n(n−1)(n−3)(n−4)!=5040

⇒n(n−1)(n−2)(n−3)=5040

⇒n=10