Question

QUESTION 2 2.1 Simplify fully without the use of a calculator: \[ \frac{2^{m+5}-3.2^{m-2}}{5.2^{m+3}} \] 2.2 Solve for \( x \) : \[ 4^{x}-5.2^{x}-24=0 \] 2.3 If \( x=\frac{3-\sqrt{a}}{\sqrt{2}} \) and \( y=\frac{4+\sqrt{a}}{\sqrt{2}} \), determine the value of \( (x+y)^{2} \).

Ask by Turnbull Mejia. in South Africa
Mar 14,2025

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Tutor-Verified Answer

Answer

- **2.1:** \(\frac{25}{32}\) - **2.2:** \(x = 3\) - **2.3:** \((x+y)^{2} = \frac{49}{2}\)

Solution

Simplify the expression by following steps: - step0: Solution: \(\frac{\left(3-\sqrt{a}\right)}{\sqrt{2}}+\frac{\left(4+\sqrt{a}\right)}{\sqrt{2}}\) - step1: Remove the parentheses: \(\frac{3-\sqrt{a}}{\sqrt{2}}+\frac{4+\sqrt{a}}{\sqrt{2}}\) - step2: Transform the expression: \(\frac{3-\sqrt{a}+4+\sqrt{a}}{\sqrt{2}}\) - step3: Calculate: \(\frac{7}{\sqrt{2}}\) - step4: Multiply by the Conjugate: \(\frac{7\sqrt{2}}{\sqrt{2}\times \sqrt{2}}\) - step5: Multiply the numbers: \(\frac{7\sqrt{2}}{2}\) Solve the equation \( 4^{x}-5*2^{x}-24=0 \). Solve the equation by following steps: - step0: Solve for \(x\): \(4^{x}-5\times 2^{x}-24=0\) - step1: Factor the expression: \(\left(2^{x}-8\right)\left(2^{x}+3\right)=0\) - step2: Separate into possible cases: \(\begin{align}&2^{x}-8=0\\&2^{x}+3=0\end{align}\) - step3: Solve the equation: \(\begin{align}&x=3\\&x \notin \mathbb{R}\end{align}\) - step4: Find the union: \(x=3\) Calculate or simplify the expression \( (2^{m+5}-3*2^{m-2})/(5*2^{m+3}) \). Simplify the expression by following steps: - step0: Solution: \(\frac{\left(2^{m+5}-3\times 2^{m-2}\right)}{\left(5\times 2^{m+3}\right)}\) - step1: Remove the parentheses: \(\frac{2^{m+5}-3\times 2^{m-2}}{5\times 2^{m+3}}\) - step2: Subtract the terms: \(\frac{125\times 2^{m-2}}{5\times 2^{m+3}}\) - step3: Reduce the fraction: \(\frac{25}{2^{5}}\) - step4: Evaluate the power: \(\frac{25}{32}\) Let's go through each part of the problem step by step. ### 2.1 Simplify the expression: We need to simplify the expression: \[ \frac{2^{m+5}-3 \cdot 2^{m-2}}{5 \cdot 2^{m+3}} \] **Step 1: Factor out common terms in the numerator.** The numerator can be rewritten as: \[ 2^{m-2}(2^{7} - 3) \] This is because \(2^{m+5} = 2^{m-2} \cdot 2^{7}\) and \(3 \cdot 2^{m-2} = 3 \cdot 2^{m-2}\). **Step 2: Substitute back into the expression.** Now, substituting this back into the expression gives: \[ \frac{2^{m-2}(2^{7} - 3)}{5 \cdot 2^{m+3}} \] **Step 3: Simplify the fraction.** We can simplify \(2^{m-2}\) and \(2^{m+3}\): \[ \frac{2^{m-2}}{2^{m+3}} = \frac{1}{2^{5}} = \frac{1}{32} \] Thus, the expression simplifies to: \[ \frac{2^{7} - 3}{5 \cdot 32} \] **Step 4: Calculate \(2^{7} - 3\).** Calculating \(2^{7} = 128\): \[ 128 - 3 = 125 \] So, we have: \[ \frac{125}{160} = \frac{25}{32} \] The fully simplified expression is: \[ \frac{25}{32} \] ### 2.2 Solve for \( x \): We need to solve the equation: \[ 4^{x}-5 \cdot 2^{x}-24=0 \] **Step 1: Rewrite \(4^{x}\) in terms of \(2^{x}\).** Since \(4^{x} = (2^{2})^{x} = 2^{2x}\), we can rewrite the equation as: \[ 2^{2x} - 5 \cdot 2^{x} - 24 = 0 \] **Step 2: Let \(y = 2^{x}\).** This transforms the equation into a quadratic form: \[ y^{2} - 5y - 24 = 0 \] **Step 3: Factor or use the quadratic formula.** Using the quadratic formula \(y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\): Here, \(a = 1\), \(b = -5\), and \(c = -24\): \[ y = \frac{5 \pm \sqrt{(-5)^{2} - 4 \cdot 1 \cdot (-24)}}{2 \cdot 1} \] Calculating the discriminant: \[ 25 + 96 = 121 \] So, \[ y = \frac{5 \pm 11}{2} \] Calculating the two possible values for \(y\): 1. \(y = \frac{16}{2} = 8\) 2. \(y = \frac{-6}{2} = -3\) (not valid since \(y = 2^{x}\) must be positive) Thus, we have: \[ 2^{x} = 8 \implies x = 3 \] ### 2.3 Determine the value of \( (x+y)^{2} \): Given: \[ x = \frac{3 - \sqrt{a}}{\sqrt{2}} \quad \text{and} \quad y = \frac{4 + \sqrt{a}}{\sqrt{2}} \] **Step 1: Calculate \(x + y\).** \[ x + y = \frac{3 - \sqrt{a}}{\sqrt{2}} + \frac{4 + \sqrt{a}}{\sqrt{2}} = \frac{(3 - \sqrt{a}) + (4 + \sqrt{a})}{\sqrt{2}} = \frac{7}{\sqrt{2}} \] **Step 2: Calculate \((x+y)^{2}\).** \[ (x+y)^{2} = \left(\frac{7}{\sqrt{2}}\right)^{2} = \frac{49}{2} \] ### Final Answers: - **2.1:** \(\frac{25}{32}\) - **2.2:** \(x = 3\) - **2.3:** \((x+y)^{2} = \frac{49}{2}\)

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To simplify the expression, consider the structure of the terms involved. In the numerator, you can factor out \( 2^{m-2} \) to make the calculation clearer: \[ \frac{2^{m+5}-3 \cdot 2^{m-2}}{5 \cdot 2^{m+3}} = \frac{2^{m-2}(2^{7}-3)}{5 \cdot 2^{m+3}} = \frac{2^{m-2}(128-3)}{5 \cdot 2^{m+3}} = \frac{125 \cdot 2^{m-2}}{5 \cdot 2^{m+3}} = \frac{125}{5 \cdot 2^{5}} = \frac{25}{32} \] But don't stop there! When you simplify further, you find that it's always useful to remember that fractions are just as tasty as cakes: stack them wisely! Now, for the second part, rearranging our equation helps. Replacing \(4^x\) with \( (2^2)^x = 2^{2x} \) allows for a neat transformation: \[ 2^{2x} - 5 \cdot 2^{x} - 24 = 0 \] Then, substituting \(y = 2^{x}\) turns the equation into a standard quadratic: \[ y^2 - 5y - 24 = 0 \] Using the quadratic formula gives us \(y = 8\) or \(y = -3\). Since \(y = 2^x\) must be a positive value, we pick \(y=8\), so \(x=3\). Fun fact: Quadratic equations often remind us of those delightful mystery puzzles! The solutions are like clues that guide you to the treasure! Lastly, for \(x+y\): \[ x+y = \frac{3-\sqrt{a}}{\sqrt{2}} + \frac{4+\sqrt{a}}{\sqrt{2}} = \frac{(3-\sqrt{a}) + (4+\sqrt{a})}{\sqrt{2}} = \frac{7}{\sqrt{2}} \] Calculating \((x+y)^2\): \[ (x+y)^2 = \left(\frac{7}{\sqrt{2}}\right)^2 = \frac{49}{2} \] When you're working with squares, remember: they’re not just a shape; they bring symmetry to the mathematical party!

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