A Level Maths Notes: C3 – Algebraic Fractions
The same rules apply for algebraic fractions as for normal fractions
When adding or subtracting, make a common denominator.
When multiplying fractions, cross cancel first if possible. Multiply the denominators together to make a new denominator. Multiply the numerators together to make a new numerator. Cancel if possible.
When dividing fractions, invert the dividing fraction and multiply.
Example: Add and simplify
Notice first that
factorises
into
The
question becomes
Example: Add and simplify if
possible:
No further simplification is possible.
Example: Multiply
by
factorises:
Hence
Since the
and
terms
cross cancel.
Example: Divide
by
factorises:
Hence
Since the
terms
cross cancel.