Given that \(f(x) = \frac{x+1}{2}\), find \(f^{1}(-2)\).

  • A -5
  • B -3
  • C \(-\frac{1}{2}\)
  • D 5
waec 2017furthermathematics

The correct answer is A. -5

Let \(f(x) = y\), then we have

\(y = \frac{x+1}{2} \implies 2y = x+1; x = 2y-1\)

Let \(f^{1}(x) = x; x = 2y-1\), replacing y with x,

\(f^{1}(x) = 2x - 1 \implies f^{1}(-2) = 2(-2) -1= -5\)

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