Math Problem Statement

Simplify the expression (n-3)! / (n-2)!

Solution

To simplify the given expression:

(n3)!(n2)!\frac{(n-3)!}{(n-2)!}

Steps:

  1. Recall the factorial property: For any integer kk, k!=k(k1)!k! = k \cdot (k-1)!

  2. Expand the denominator (n2)!(n-2)! in terms of (n3)!(n-3)!: (n2)!=(n2)(n3)!(n-2)! = (n-2) \cdot (n-3)!

  3. Substitute this expansion into the denominator: (n3)!(n2)!=(n3)!(n2)(n3)!\frac{(n-3)!}{(n-2)!} = \frac{(n-3)!}{(n-2) \cdot (n-3)!}

  4. Cancel (n3)!(n-3)! in the numerator and denominator: (n3)!(n2)(n3)!=1n2\frac{(n-3)!}{(n-2) \cdot (n-3)!} = \frac{1}{n-2}

Final Simplified Expression:

1n2\frac{1}{n-2}

Let me know if you'd like further clarification!

Follow-up questions:

  1. What is the general rule for simplifying factorial expressions?
  2. How can factorial expressions be used in combinations or permutations?
  3. What happens if n=2n = 2 in this expression?
  4. Can you generalize a similar simplification for (nk)!(nm)!\frac{(n-k)!}{(n-m)!}?
  5. How would you compute this expression for specific values of nn?

Tip:

When simplifying factorial expressions, always expand the larger factorial to include the smaller one for easier cancellation.

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Math Problem Analysis

Mathematical Concepts

Factorials
Simplification of expressions
Algebra

Formulas

Factorial property: k! = k × (k-1)!
Simplification: Expand larger factorials in terms of smaller ones

Theorems

Properties of Factorials

Suitable Grade Level

Grades 9-12