大象传媒

Transformation of curves - Higher - EdexcelTranslating graphs

Functions of graphs can be transformed to show shifts and reflections. Graphic designers and 3D modellers use transformations of graphs to design objects and images.

Part of MathsAlgebra

Translating graphs

The translation of graphs is explored

A translation is a movement of the graph either horizontally parallel to the \(x\)-axis or vertically parallel to the \(y\)-axis.

Functions

The graph of \(f(x) = x^2\) is the same as the graph of \(y = x^2\). Writing graphs as functions in the form \(f(x)\) is useful when applying translations and reflections to graphs.

Translations parallel to the y-axis

If \(f(x) = x^2\), then \(f(x) + a = x^2 + a\). Here we are adding \(a\) to the whole function.

The addition of the value \(a\) represents a vertical translation in the graph. If \(a\) is positive, the graph translates upwards. If \(a\) is negative, the graph translates downwards.

Example 1

\(f(x) = x^2\)

\(f(x) + 3 = x^2 + 3\)

Graph showing plots of f(x)+3=x^2+3 & f(x)=x^2

Example 2

\(f(x) = x^2\)

\(f(x) - 2 = x^2 - 2\)

Graph showing plots of f(x)-2=x^2-2 & f(x)=x^2

\(f(x) + a\) represents a translation through the vector \(\begin{pmatrix} 0 \\ a \end{pmatrix}\).

Translations parallel to the x-axis

If \(f(x) = x^2\) then \(f(x + a) = (x + a)^2\).

Here we add \(a\) to \(x\), not to the whole function. This time we will get a horizontal translation. If \(a\) is positive then the graph will translate to the left. If the value of \(a\) is negative, then the graph will translate to the right.

Example 1

\(f(x) = x^2\)

\(f(x + 3) = (x + 3)^2\)

Graph showing plots of f(x+3)=(x+3)^2 & f(x)=x^2

Example 2

\(f(x) = x^2\)

\(f(x - 2) = (x - 2)^2\)

Graph showing plots of f(x-2)=(x-2)^2 & f(x)=x^3

\(f(x + a)\) represents a translation through the vector \(\begin{pmatrix} -a \\ 0 \end{pmatrix}\).