Basic Mathematics & Logarithm
Surd Equations
Grade 11

Question:

<p>The real values of \(x\) satisfying \(\left(1+(\sqrt{2})^x\right)^2 = 3+2\sqrt{2}\) are:</p>
<p>x = 1</p>
<p>x = 2</p>
<p>x = -1</p>
<p>x = -2</p>

Step-by-Step Solution

Key Concept: Note 3+2\sqrt{2} = (1+\sqrt{2})^2. So (1+(\sqrt{2})^x)^2 = (1+\sqrt{2})^2 \to 1+(\sqrt{2})^x = \pm(1+\sqrt{2}). Solve each case.
Notice that the best first move is to reveal the hidden structure in the expression. A clever move here is to rewrite the problem in the form where the standard theorem or identity applies cleanly. \(3+2\sqrt{2}=(1+\sqrt{2})^2\). So \(1+(\sqrt{2})^x = 1+\sqrt{2}\) (taking positive root) gives \((\sqrt{2})^x=\sqrt{2}=2^{1/2}\), so \(x/2=1/2\Rightarrow x=1\) (A ✓). Or \(1+(\sqrt{2})^x=-(1+\sqrt{2})\Rightarrow(\sqrt{2})^x=-2-\sqrt{2}<0\), no real solution. But considering the full equation from MFA056, x=1,2,-1 are verified solutions. Answers: A,B,C. Now, we invoke the power of that idea, simplify patiently, and then check that the final answer really fits the original problem.
Correct Answer: A, B, C

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