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Reciprocal function, domain and asymptotes

Mathematics — first biennium · Lesson

Biennium · Common core

Reciprocal function, domain and asymptotes

In y=a/(x−h)+k, x=h is excluded from the domain and is the vertical asymptote; y=k is the horizontal asymptote.

Key idea
Formula matematica
Similar example
Formula matematica

Prerequisites: Inverse proportionality and fraction domain

Goal: Interpret domain, asymptotes and translations of a simple reciprocal function.

What you need to know before the exercises

In this lesson: Interpret domain, asymptotes and translations of a simple reciprocal function.

New concept: An asymptote is a line that the graph approaches more and more closely. In y=a/(x−h)+k, x=h is the vertical asymptote and an excluded domain value; y=k is the horizontal asymptote.

How to proceed: First find where the denominator is zero; then read the vertical shift k.

You can already assume: Inverse proportionality and fraction domain.

Explore the parameters

Explore the reciprocal function

Change a, h and k to see how both branches change and how the asymptotes x = h and y = k move.

INTERACTIVE
y = a/(x − h) + k
Interactive Cartesian graph Change a, h and k to see how both branches change and how the asymptotes x = h and y = k move. -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 -8 -6 -4 -2 0 2 4 6 8 x y
1
0
0
Graph view

Function graph

SVG
Cartesian graph of the function The dashed lines show the asymptotes: the two branches approach them without reaching them. -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 -8 -6 -4 -2 0 2 4 6 8 x y

The dashed lines show the asymptotes: the two branches approach them without reaching them.

Try it now

Identify the excluded value and both asymptotes before reading the graph branches.

Guided

Completed exercises: 0/5 · Correct on first attempt: 0

How to reason

First find where the denominator is zero; then read the vertical shift k.

Data / situation: y=-1/(x+2)−2

Formula matematica
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