20 problems. Master the 3 key patterns and ace your exam.
Key 1 · DOS
a2 − b2 = (a+b)(a−b)
No middle term → Difference of Squares
Key 2 · PST+
a2+2ab+b2 = (a+b)2
Positive middle → Perfect Square (plus)
Key 3 · PST−
a2−2ab+b2 = (a−b)2
Negative middle → Perfect Square (minus)
Key 4 · GCF FIRST
Always factor out GCF first!
Then apply DOS or PST to the rest
Trick · PST Check
2·√(1st)·√(last) = middle?
If YES → it’s a Perfect Square Trinomial