If np6=20×np4, then find the value of n
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Answer:
n=7
Step-by-step explanation:
Correct option is
A
7
n
P
4
=20×
n
P
2
⇒
(n−4)!
n!
=20
(n−2)!
n!
⇒(n−2)(n−3)=20
⇒n
2
−5n−114=0
⇒(n−7)(n+2)=0
n=7,−2
As n>0
⇒
n=7
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SIMILAR QUESTIONS
star-struck
Find the value of n such that
n
P
5
=42(
n
P
3
):n>4.
Hard
View solution
>
If 5.
n
P
3
=4.
n+1
P
3
,
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