1. FACTORISATION OF A TRINOMIAL
A trinomial is factorised by changing into a double bracket.
x2 + bx + c where b & c are integers
Last term positive:
Both number terms need to be the same sign.
If the middle term is POSITIVE both signs POSITIVE.
If the middle term is NEGATIVE both signs NEGATIVE.
Last term negative:
The number terms are different signs.
If the middle term is POSITIVE the largest number is POSITIVE.
If the middle term is NEGATIVE the largest number is NEGATIVE.

2. Example:
x2 – 2x – 35 =
v2 + 9v + 20 =
s2 – 7s + 10 =
p2 + 4p – 21 =
(x – 7)(x + 5)
(v + 5)(v + 4)
(s – 5)(s – 2)
(p + 7)(p – 3)