Chapter 5

Transformations and symmetry

Shift, reflect and stretch graphs, test functions for even and odd symmetry, and work with absolute value, composite functions and piecewise functions.

Sections

  1. 5A Translations of known graphs Shift a graph left, right, up and down by changing its equation, and use translations to find the vertex of a parabola or the centre of a circle.
  2. 5B Reflections in the axes Reflect a graph in the y-axis by replacing x with −x, in the x-axis by replacing y with −y, and in both axes at once (a rotation of 180° about the origin).
  3. 5C Even and odd functions Recognise even functions (symmetric in the y-axis) and odd functions (symmetric about the origin), and test any function algebraically by substituting −x.
  4. 5D Horizontal and vertical dilations Stretch a graph horizontally by replacing x with x/a, vertically by multiplying the function by b, and handle fractional and negative factors.
  5. 5E The absolute value function Absolute value as distance from zero, its piecewise definition, graphs of y = a|x − h| + k, solving absolute value equations, and useful identities.
  6. 5F Composite functions Form composite functions f(g(x)) and g(f(x)), evaluate them, and find the domain and range of a composite.
  7. 5G Combining transformations Apply several transformations in order, write the resulting equation, and know which pairs of transformations commute and which do not.
  8. 5H Continuity and piecewise-defined functions What it means for a function to be continuous at a point, how to sketch piecewise-defined functions, and how to test whether the pieces join up.

Formula sheet