If 2^(x + 3) = 8^(x - 1), find the value of x.
Answer and explanation
Correct answer: B. 3
- Step 1: Express 8 as power of 2: 8 = 2³. Step 2. Right side becomes 2^[3(x - 1)] = 2^(3x - 3). Step 3. Equate exponents: x + 3 = 3x - 3. Step 4. Solve: 2x = 6 => x = 3. Answer: 3. Why not the others: 2 gives 2⁵ = 32 and 8¹ = 8 (32 ≠ 8); 4 gives 2⁷ = 128 and 8³ = 512; 1 gives 2⁴ = 16 and 8⁰ = 1.
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