Mathematics – DBE 2025 MayJune – Question 1.1.3 – Algebra

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The Question

Solve for x: 2^(x+4)+2^x = 8704

Details

Subject: Mathematics

Year: DBE_2025_MayJune

Paper: 1

Question Number: 1.1.3

Difficulty: Medium

Marks: 3

Topic: Algebra – Exponential Equations

💡 Hint

Look for ways to simplify the terms with ‘x’ in the exponent. Can you use exponent rules to create a common factor?

📝 Solution Steps

  1. Apply exponent rules to expand terms like 2^(x+4).
  2. Factor out the common exponential term.
  3. Simplify the numerical part of the equation.
  4. Isolate the exponential term (e.g., 2^x).
  5. Express the constant on the right side as a power of the same base as the exponential term.
  6. Equate the exponents to solve for x.

📚 Explanation

This is an exponential equation. The trick here is to use exponent rules to simplify the left side. Remember that a^(m+n) = a^m * a^n. So, 2^(x+4) can be rewritten as 2^x * 2^4. Now the equation becomes 2^x * 2^4 + 2^x = 8704. You can factor out the common term 2^x: 2^x * (2^4 + 1) = 8704. Calculate 2^4, which is 16. So, 2^x * (16 + 1) = 8704, which simplifies to 2^x * 17 = 8704. Divide both sides by 17 to get 2^x = 512. Finally, express 512 as a power of 2 (512 = 2^9). Since the bases are the same, you can equate the exponents: x=9.

✅ Answer

x = 9

⚠️ Common Mistakes

  • Incorrect application of exponent rules (e.g., adding exponents when multiplying bases).
  • Calculation errors when simplifying numerical terms.

📐 Formulas Required

  • a^(m+n) = a^m * a^n

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