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The number of real roots of the equation...

The number of real roots of the equation
`5+|2^(x)-1|=2^(x)(2^(x)-2)` is

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To find the number of real roots of the equation \[ 5 + |2^x - 1| = 2^x(2^x - 2), \] we will analyze the equation by considering two cases based on the expression inside the absolute value. ### Step 1: Analyze the cases for the absolute value We will consider two cases based on the expression \(2^x - 1\): 1. **Case 1**: \(2^x - 1 \geq 0\) (i.e., \(x \geq 0\)) 2. **Case 2**: \(2^x - 1 < 0\) (i.e., \(x < 0\)) ### Step 2: Solve Case 1 In Case 1, since \(2^x - 1 \geq 0\), we can replace \(|2^x - 1|\) with \(2^x - 1\). The equation becomes: \[ 5 + (2^x - 1) = 2^x(2^x - 2). \] Simplifying this gives: \[ 5 + 2^x - 1 = 2^x(2^x - 2), \] \[ 4 + 2^x = 2^{2x} - 2^{x + 1}. \] Rearranging leads to: \[ 2^{2x} - 2^{x + 1} - 2^x - 4 = 0. \] Let \(t = 2^x\). Then we can rewrite the equation as: \[ t^2 - 2t - 4 = 0. \] ### Step 3: Solve the quadratic equation Using the quadratic formula \(t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\): \[ t = \frac{2 \pm \sqrt{(-2)^2 - 4 \cdot 1 \cdot (-4)}}{2 \cdot 1}, \] \[ t = \frac{2 \pm \sqrt{4 + 16}}{2}, \] \[ t = \frac{2 \pm \sqrt{20}}{2}, \] \[ t = \frac{2 \pm 2\sqrt{5}}{2}, \] \[ t = 1 \pm \sqrt{5}. \] Since \(t = 2^x\) must be positive, we only consider \(t = 1 + \sqrt{5}\). ### Step 4: Find \(x\) Now we find \(x\): \[ 2^x = 1 + \sqrt{5} \implies x = \log_2(1 + \sqrt{5}). \] ### Step 5: Solve Case 2 In Case 2, since \(2^x - 1 < 0\), we replace \(|2^x - 1|\) with \(-(2^x - 1)\): \[ 5 - (2^x - 1) = 2^x(2^x - 2). \] This simplifies to: \[ 5 - 2^x + 1 = 2^{2x} - 2^{x + 1}, \] \[ 6 - 2^x = 2^{2x} - 2^{x + 1}. \] Rearranging gives: \[ 2^{2x} - 2^{x + 1} + 2^x - 6 = 0. \] Let \(m = 2^x\): \[ m^2 - 2m + m - 6 = 0 \implies m^2 - m - 6 = 0. \] ### Step 6: Solve the quadratic equation for Case 2 Using the quadratic formula again: \[ m = \frac{1 \pm \sqrt{1 + 24}}{2} = \frac{1 \pm 5}{2}. \] This gives: \[ m = 3 \quad \text{or} \quad m = -2. \] Since \(m = 2^x\) must be positive, we take \(m = 3\). ### Step 7: Find \(x\) for Case 2 \[ 2^x = 3 \implies x = \log_2(3). \] ### Step 8: Combine results From both cases, we have two solutions: 1. \(x = \log_2(1 + \sqrt{5})\) from Case 1. 2. \(x = \log_2(3)\) from Case 2. ### Conclusion Thus, the number of real roots of the equation is: \[ \boxed{2}. \]

To find the number of real roots of the equation \[ 5 + |2^x - 1| = 2^x(2^x - 2), \] we will analyze the equation by considering two cases based on the expression inside the absolute value. ...
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