Question

nP4=18.^n-1 P2 what is the value of n

Answer 1

Step-by-step explanation:

nP4 = n(n-1)(n-2)(n-3)

10*(n-1)P2 = 10(n-1)(n-2)

equating and cancelling out common terms,

10 = n(n-3)

expand as a standard quadratic

n^2 -3n - 10 =0

factorise

(n-5)(n+2) = 0

take positive value

n = 5

====

Answer 2

Step-by-step explanation:

np4=n(n-1)(n-2)(n-3)

10*(n-1)p2=10(n-1)(n-2)

equating and cancelling common terms,

10=n(n-3)

expand as standard quadratic

n^2-3n-10=0

factorise

(n-5)(n+2)=0

take positive value

n=5