Math Problem Statement

Two finite sets having m and n elements. The total number of subsets of the first set is 56 more than the total number of subsets of the second set.find the value of m and b

Solution

To solve the problem, let's break it down step by step.

Given:

  1. The number of subsets of a finite set with kk elements is 2k2^k.
  2. For two sets with mm and nn elements, the total number of subsets of the first set is 2m2^m, and the total number of subsets of the second set is 2n2^n.
  3. It is given that: 2m=2n+562^m = 2^n + 56

Step 1: Express the relationship

From the equation 2m=2n+562^m = 2^n + 56, rearrange: 2m2n=562^m - 2^n = 56 Factorize the left-hand side using the property 2m2n=2n(2mn1)2^m - 2^n = 2^n(2^{m-n} - 1): 2n(2mn1)=562^n(2^{m-n} - 1) = 56

Step 2: Solve for nn and mnm-n

  1. Since 2n2^n is a power of 2, and 56=23756 = 2^3 \cdot 7, 2n2^n must divide 5656. Thus, possible values of 2n2^n are 1,2,4,8,16,1, 2, 4, 8, 16, etc., but only those 56\leq 56: 1,2,4,81, 2, 4, 8.

  2. For each value of 2n2^n, solve 2n(2mn1)=562^n(2^{m-n} - 1) = 56 to check for integer solutions.

Case 1: 2n=82^n = 8 (n=3n = 3)

8(2m31)=568(2^{m-3} - 1) = 56 Divide by 8: 2m31=72^{m-3} - 1 = 7 2m3=82^{m-3} = 8 m3=3    m=6m-3 = 3 \implies m = 6

Case 2: 2n=42^n = 4 (n=2n = 2)

4(2m21)=564(2^{m-2} - 1) = 56 Divide by 4: 2m21=142^{m-2} - 1 = 14 2m2=152^{m-2} = 15 But 1515 is not a power of 2, so this case fails.

Case 3: 2n=22^n = 2 (n=1n = 1)

2(2m11)=562(2^{m-1} - 1) = 56 Divide by 2: 2m11=282^{m-1} - 1 = 28 2m1=292^{m-1} = 29 But 2929 is not a power of 2, so this case fails.

Step 3: Verify solution

The only solution is: m=6,n=3m = 6, \, n = 3

Final Answer:

The values of mm and nn are: m=6,n=3m = 6, \, n = 3

Would you like to see a detailed explanation of the verification process or alternate approaches?


Related Questions:

  1. How many total subsets does a set with nn elements have?
  2. What is the relationship between 2m2^m and 2n2^n in this problem?
  3. If the difference between the subsets of two sets were 120, what would be the new values of mm and nn?
  4. How is the property 2a2b=2b(2ab1)2^a - 2^b = 2^b(2^{a-b} - 1) useful in such problems?
  5. Can this problem be generalized to sets with infinite elements?

Tip:

Always express powers of two explicitly and use factorization techniques for solving equations involving 2k2^k.

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Math Problem Analysis

Mathematical Concepts

Algebra
Exponents and Powers
Set Theory

Formulas

Number of subsets of a set with k elements: 2^k
Equation: 2^m = 2^n + 56
Factorization: 2^m - 2^n = 2^n(2^{m-n} - 1)

Theorems

Properties of exponents
Factorization of differences of powers

Suitable Grade Level

Grades 10-12