Multiple Choice Question (MCQ)
If f : R → R such that f(x)=5x+4 then which of the following is equal to f^{-1}(x).
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×
\dfrac{x-5}{4}
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✓
\dfrac{x-4}{5}
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×
\dfrac{x+4}{5}
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×
\dfrac{x}{5} -4
Answer
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Let y=5x+4
Express x in terms of y
x=\dfrac{y-4}{5}
Therefore, its inverse function is
f^{-1}(x)=\dfrac{x-4}{5}