Changing the Subject / Manipulating Surds Summary

Changing the Subject and Manipulating Surds


two types of useful algebraic skills and techniques are changing the subject of a formula and dealing with surds and roots.

often a formula will contain several variables and will require re-arrangement to make a particular variable the subject of the formula.

surds are irrational terms or numbers given in the form of a root. surds can be manipulated using the usual rules of algebra.

algebraic fractions containing irrational surds or roots in the denominator should be rationalised.

equations involving surds and roots can often be solved by squaring each side of the equation.

Key Skills


  • change the subject of a formula
  • expand expressions involving surds
  • rationalise denominators
  • solve equations involving surds


surddenominatorrationaliseroot, irrational numberformula,subject.