Inverse Functions: Reflection of f(x) & g(x) Logic

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SUMMARY

The discussion centers on the logic of inverse functions, specifically how the coordinates of a function \(f(x)\) relate to its inverse \(g(x)\). It establishes that for a point \((x, f(x))\) on the graph of \(f(x)\), the corresponding point on \(g(x)\) is \((f(x), x)\). The discussion also highlights that the locus of mid-points between these points is \(\left(\frac{x+f(x)}{2}, \frac{x+f(x)}{2}\right)\), indicating that the line of symmetry for these functions is \(y = x\).

PREREQUISITES
  • Understanding of inverse functions in mathematics
  • Familiarity with Cartesian coordinates
  • Knowledge of symmetry in graphs
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study the properties of inverse functions in detail
  • Explore graphical representations of functions and their inverses
  • Learn about the significance of the line of symmetry in function graphs
  • Investigate the implications of mid-point calculations in coordinate geometry
USEFUL FOR

Students studying mathematics, educators teaching inverse functions, and anyone interested in understanding the geometric relationships between functions and their inverses.

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Can anyone explain the logic behind the answer?

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Taken from HiSet free practice test
 

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Suppose we have the point:

$$(x,f(x))$$

on the plot of \(f(x)\). Then, on the plot of \(g(x)\), we must have the corresponding point:

$$(f(x),x)$$

Now, consider that for all possible points, the locus of the mid-points is:

$$\left(\frac{x+f(x)}{2},\frac{x+f(x)}{2}\right)$$

Thereby implying that the line of symmetry must be:

$$y=x$$
 

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