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(1) \( 2^{2 x}=2^{2}\left(2^{x}+8\right) \)

Ask by Gordon Powell. in South Africa
Jan 26,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

The solution is \( x = 3 \).

Solution

To solve the equation: \[ 2^{2x} = 2^{2}\left(2^{x} + 8\right) \] let's follow these steps: ### Step 1: Simplify the Equation First, recognize that \(2^{2x}\) can be rewritten as \((2^{x})^{2}\): \[ (2^{x})^{2} = 2^{2} \left(2^{x} + 8\right) \] ### Step 2: Substitute for Simplification Let’s make a substitution to simplify the equation. Let: \[ y = 2^{x} \] The equation becomes: \[ y^{2} = 4(y + 8) \] ### Step 3: Rearrange the Equation Bring all terms to one side to form a quadratic equation: \[ y^{2} - 4y - 32 = 0 \] ### Step 4: Solve the Quadratic Equation Use the quadratic formula to solve for \(y\): \[ y = \frac{4 \pm \sqrt{(-4)^2 - 4 \cdot 1 \cdot (-32)}}{2 \cdot 1} \] \[ y = \frac{4 \pm \sqrt{16 + 128}}{2} \] \[ y = \frac{4 \pm \sqrt{144}}{2} \] \[ y = \frac{4 \pm 12}{2} \] This gives two possible solutions: 1. \( y = \frac{4 + 12}{2} = \frac{16}{2} = 8 \) 2. \( y = \frac{4 - 12}{2} = \frac{-8}{2} = -4 \) ### Step 5: Consider the Validity of Solutions Since \( y = 2^{x} \) and any exponential expression with base 2 is always positive, \( y = -4 \) is not a valid solution. Therefore, we have: \[ y = 8 \] ### Step 6: Solve for \( x \) Recall that \( y = 2^{x} \): \[ 2^{x} = 8 \] Since \( 8 = 2^{3} \), we have: \[ 2^{x} = 2^{3} \implies x = 3 \] ### Conclusion The solution to the equation is: \[ \boxed{3} \]

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Bonus Knowledge

To solve the equation \( 2^{2x}=2^{2}(2^{x}+8) \), you can start by rewriting the right-hand side: 1. \( 2^{2x} = 4(2^x + 8) \) 2. Now, divide both sides by 4: \[ \frac{2^{2x}}{4} = 2^{x} + 8 \] 3. This simplifies to: \[ 2^{2x - 4} = 2^{x} + 8 \] Next, let \( y = 2^x \): 1. Substitute \( y \) into the equation: \[ \frac{y^2}{4} = y + 8 \] 2. Multiply through by 4 to eliminate the fraction: \[ y^2 = 4y + 32 \] 3. Rearrange into standard quadratic form: \[ y^2 - 4y - 32 = 0 \] Now, you can solve this quadratic equation using the quadratic formula \( y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): 1. Here, \( a = 1, b = -4, c = -32 \). 2. Calculate the discriminant: \[ b^2 - 4ac = (-4)^2 - 4(1)(-32) = 16 + 128 = 144 \] 3. Apply the quadratic formula: \[ y = \frac{4 \pm \sqrt{144}}{2} = \frac{4 \pm 12}{2} \] This gives: 1. \( y = \frac{16}{2} = 8 \) or \( y = \frac{-8}{2} = -4 \) (negative values don't apply since \( y = 2^x \) is always positive). 2. So, \( y = 8 \). Now, revert back to \( x \): \[ 2^x = 8 \] Thus, since \( 8 = 2^3 \), we have: \[ x = 3 \] The final solution is \( x = 3 \).

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