Question:medium

The number of real-valued solutions of the equation \(2^x+2^{-x}=2-(x-2)^2\) is

Updated On: Jan 15, 2026
  • infinite
  • 1
  • 0
  • 2
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The Correct Option is C

Solution and Explanation

The given equation is:

\(2^x + 2^{-x} = 2 - (x - 2)^2\)

Analysis of each side follows.

Left-Hand Side (LHS): \(2^x + 2^{-x}\)

  • For any real \(x\), both \(2^x\) and \(2^{-x}\) are positive.
  • By the AM ≥ GM inequality:
    \[ 2^x + 2^{-x} \geq 2\sqrt{2^x \cdot 2^{-x}} = 2 \] Equality holds when \(2^x = 2^{-x}\), which implies \(x = 0\).
  • Therefore, LHS ≥ 2, with equality occurring exclusively at \(x = 0\).

Right-Hand Side (RHS): \(2 - (x - 2)^2\)

  • For any real \(x\), \((x - 2)^2\) is non-negative.
  • The maximum value of the RHS is achieved when \((x - 2)^2 = 0\), which occurs at \(x = 2\).
  • At \(x = 2\), RHS = 2. For all other values of \(x\), RHS<2.

Comparison of LHS and RHS

  • The LHS is always ≥ 2, reaching equality at \(x = 0\).
  • The RHS is always ≤ 2, reaching equality at \(x = 2\).
  • Consequently, no value of \(x\) exists for which both sides are equal.

Thus, there are no real solutions to the equation.

Final Answer: \(0\) real-valued solutions.

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