IGCSE Maths Notes: Transformations of Graphs
We can sort transformations of graphs into two types -x transformations or y transformations. Anything else is a combination of an x transformation followed by a y transformation or vice versa.
A transformation is an x transformation if it is an argument of a function on the right hand side, or if it can be written in brackets without looking like nonsense. For instance, these are some x transformations:
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x transformations are always counter – intuitive..To
transform
you
might think you scale by 2 in the x direction. THIS IS WRONG!!! You
scale by
Your
graph becomes compressed in the x – direction, not expanded. And to
transform
you
do not subtract 2 from all the x's, hence moving the graph left. You
add 2 to all the s's and move the graph right.
Y transformations are easier.
implies
correctly, a scaling by 2 in the y direction. Notice the difference
between sin2x or sin(2x) which is an x transformation and 2sinx ,
which is a y transformation. These are some more examples of y
transformations:
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y transformations are always intuitive. To
transform
you
move the graph up 1, and for
we
scale by 4 in the y direction.
Sometimes we can have a combination of transformations:
represents
a scaling by 3 in the y direction FOLLOWED by a movement up 2. It
would be wrong to do it the other way round.
represents
a scaling of 3 in the y direction and a scaling by
in
the x direction. This is illustrated above.