Sets, Relations & Functions
Cardinality and Subsets
Grade 11

Question:

<p>The total possible subsets of sets A and B are \(2^m\) and \(2^n\) respectively. If \(2^m - 2^n = 56\) and \(2^{m-n} = \frac{3}{2}\), find \(m + n\).</p>

Step-by-Step Solution

Key Concept: Factor out common powers of 2 and use the given relationships to solve for m and n.
<p><strong>Solution:</strong></p><p>Given: $2^m - 2^n = 56$ and $2^{m-n} = \frac{3}{2}$</p><p>From the first equation: $2^n(2^{m-n} - 1) = 56$</p><p>On comparing: $2^n = 2^3$ and $2^{m-n} = 2^3$</p><p>Therefore: $n = 3$ and $m - n = 3$</p><p>Thus: $m = 6$ and $n = 3$</p><p>Therefore: $m + n = 6 + 3 = 9$</p>
Correct Answer: 9

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