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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.1.40c

What can you conclude about the inverses of functions whose graphs are lines perpendicular to the line y=x?

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1
Recall that the line \(y = x\) has a slope of 1. Lines perpendicular to \(y = x\) have slopes that are the negative reciprocal of 1, which is \(-1\).
Consider a function \(f(x)\) whose graph is a line perpendicular to \(y = x\). Such a function can be written as \(f(x) = -x + b\), where \(b\) is the y-intercept.
To find the inverse function \(f^{-1}(x)\), start by replacing \(f(x)\) with \(y\): \(y = -x + b\). Then, swap \(x\) and \(y\) to get \(x = -y + b\).
Solve the equation \(x = -y + b\) for \(y\) to find the inverse function: \(y = -x + b\). Notice that the inverse has the same form as the original function.
Conclude that the inverse of a function whose graph is a line perpendicular to \(y = x\) is another line with the same slope \(-1\), meaning the inverse function is also perpendicular to \(y = x\) and has the same slope as the original function.

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