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Solve for \( x \) : (a) \( 3^{x}=1 \) (d) \( \left(\frac{1}{9}\right)^{x}=27 \) (g) \( 4\left(\frac{1}{4}\right)^{x-1}=8 \) (j) \( \frac{3^{2 x-1}}{3^{x}}=3 \) (m) \( 8^{-x}-2.4^{x-1}=0 \)

Ask by Norris Guzman. in South Africa
Jan 24,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

Solutions: - (a) \( x = 0 \) - (d) \( x = -\frac{3}{2} \) - (g) \( x = \frac{1}{2} \) - (j) \( x = 2 \) - (m) \( x = \frac{1}{5} \)

Solution

Let's solve each equation step by step. --- ### **Problem (a):** \( 3^{x} = 1 \) **Solution:** We know that any non-zero number raised to the power of 0 is 1. Therefore: \[ 3^{x} = 1 \implies x = 0 \] **Answer:** \( x = 0 \) --- ### **Problem (d):** \( \left(\frac{1}{9}\right)^{x} = 27 \) **Solution:** First, express both sides with the same base. Notice that \( \frac{1}{9} = 9^{-1} = 3^{-2} \) and \( 27 = 3^{3} \). \[ \left(3^{-2}\right)^{x} = 3^{3} \implies 3^{-2x} = 3^{3} \] Since the bases are the same, set the exponents equal: \[ -2x = 3 \implies x = -\frac{3}{2} \] **Answer:** \( x = -\frac{3}{2} \) --- ### **Problem (g):** \( 4\left(\frac{1}{4}\right)^{x-1} = 8 \) **Solution:** First, express \( \frac{1}{4} \) and 8 with base 2: \[ \frac{1}{4} = 2^{-2}, \quad 8 = 2^{3} \] Substitute: \[ 4 \cdot \left(2^{-2}\right)^{x-1} = 2^{3} \implies 4 \cdot 2^{-2(x-1)} = 2^{3} \] Express 4 as \( 2^2 \): \[ 2^{2} \cdot 2^{-2x + 2} = 2^{3} \implies 2^{2 - 2x + 2} = 2^{3} \implies 2^{4 - 2x} = 2^{3} \] Set exponents equal: \[ 4 - 2x = 3 \implies -2x = -1 \implies x = \frac{1}{2} \] **Answer:** \( x = \frac{1}{2} \) --- ### **Problem (j):** \( \frac{3^{2x-1}}{3^{x}} = 3 \) **Solution:** Simplify the left side using the laws of exponents: \[ \frac{3^{2x-1}}{3^{x}} = 3^{2x-1 - x} = 3^{x - 1} \] Set equal to the right side: \[ 3^{x - 1} = 3^{1} \implies x - 1 = 1 \implies x = 2 \] **Answer:** \( x = 2 \) --- ### **Problem (m):** \( 8^{-x} - 2 \cdot 4^{x-1} = 0 \) **Solution:** First, express 8 and 4 with base 2: \[ 8 = 2^{3}, \quad 4 = 2^{2} \] Substitute into the equation: \[ (2^{3})^{-x} - 2 \cdot (2^{2})^{x-1} = 0 \implies 2^{-3x} - 2 \cdot 2^{2x - 2} = 0 \] Simplify: \[ 2^{-3x} - 2^{2x - 1} = 0 \] Let \( y = 2^{x} \). Then: \[ y^{-3} - \frac{y^{2}}{2} = 0 \implies \frac{1}{y^{3}} = \frac{y^{2}}{2} \] Multiply both sides by \( 2y^{3} \): \[ 2 = y^{5} \implies y = 2^{1/5} \] Since \( y = 2^{x} \): \[ 2^{x} = 2^{1/5} \implies x = \frac{1}{5} \] **Answer:** \( x = \frac{1}{5} \) ---

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Extra Insights

To solve each of these equations, we can use the properties of exponents and logarithms. Let’s delve into the solutions: (a) \( 3^{x} = 1 \) Since any base raised to the power of 0 equals 1, we know that \( x = 0 \). (d) \( \left(\frac{1}{9}\right)^{x} = 27 \) Rewriting \( \frac{1}{9} \) as \( 9^{-1} \), we have \( (9^{-1})^{x} = 27 \). Since \( 27 = 3^3 \) and \( 9 = 3^2 \), we get \( (3^{-2})^{x} = 3^3 \). Thus, \( -2x = 3 \) or \( x = -\frac{3}{2} \). (g) \( 4\left(\frac{1}{4}\right)^{x-1} = 8 \) This can be rewritten as \( 4 \cdot 4^{-(x-1)} = 8 \), simplifying to \( 4^{1 - (x - 1)} = 8 \) or \( 4^{2 - x} = 2^3 \). Converting bases gives us \( 4^{2 - x} = (2^2)^{2-x} = 2^{2(2-x)} = 2^3 \), leading to \( 2(2-x) = 3 \), from which \( 2 - x = \frac{3}{2} \) and \( x = -\frac{1}{2} \). (j) \( \frac{3^{2x-1}}{3^{x}} = 3 \) We can simplify this to \( 3^{2x - 1 - x} = 3 \) or \( 3^{x - 1} = 3^1 \). Therefore, \( x - 1 = 1 \), giving us \( x = 2 \). (m) \( 8^{-x} - 2 \cdot 4^{x - 1} = 0 \) Rewriting as \( 8^{-x} = 2 \cdot 4^{x - 1} \), and recognizing that \( 8 = 2^3 \) and \( 4 = 2^2 \), we can express that as \( (2^3)^{-x} = 2 \cdot (2^2)^{x-1} \). This leads to \( 2^{-3x} = 2^{1 + 2(x-1)} \), simplifying to \( -3x = 1 + 2x - 2 \), or \( -3x = 2x - 1 \). Therefore, \( -5x = -1 \) gives \( x = \frac{1}{5} \). To recap: - (a) \( x = 0 \) - (d) \( x = -\frac{3}{2} \) - (g) \( x = -\frac{1}{2} \) - (j) \( x = 2 \) - (m) \( x = \frac{1}{5} \)

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