Recognise the pattern
Mental-math trick
Practice
(a + b)²
(a − b)²
a² − b²
New example
Perfect square
a² + 2ab + b²
= (a + b)²
Perfect square
a² − 2ab + b²
= (a − b)²
Difference of squares
a² − b²
= (a + b)(a − b)