If = 2 : 1, find the value of n.
Given Equation :
To Find : Value of n
Formula :
By given equation,
By using above formula,
Cancelling terms (n - 4)! And (2!),
∴ (n - 2) × (n - 3) = 6
∴ (n - 2) × (n - 3) = (3) × (2)
By comparing both the sides,
Conclusion : Value of n is 5.
Note : Instead of taking product of two brackets in eq(1), it is easy to convert the constant term that is 6 into product of two consecutive numbers and then by observing two sides of equation we can get value of n.