07Cdiff2squares

= Difference of Two Squares =

Recall that if we use FOIL to expand (x + y)(x - y), we get:
 * This occurs every time the two brackets are the same except that the sign in the middle swaps from plus to minus.
 * This is referred to as ** the difference of two squares ** (ie subtraction between two terms that have been squared).

We can __reverse__ this result to get a rule for factorising.

Factorising the Difference of Two Squares.
Anytime we see two squared terms with a minus between them, we can factorise using this rule:

** Example 1 **
Factorise
 * a² – 25
 * 4a² – 9b²
 * 6x² – 6


 * Solution:**

** Example 2 **
Factorise
 * c² – 10
 * (d + 3)² – 16


 * Solution:**



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