The formula
(a + b)2 = a2 + b2 + 2ab
Working forwards - Expansion
For example, the expression (2x + 3y)
2 can be expanded as follows:
= (2x)2 + (3y)2 + 2(2x)(3y)
= 4x2 + 9y2 + 12xy
Working backwards - Factorization
For example, the expression x
2 + 100y
2 + 20xy can be factored as follows:
x2 + (10y)2 + 2(x)(10y)
On comparing it with a
2 + b
2 + 2ab
(x + 10y)2
.. which is the factored form.
http://blogformathematics.blogspot.com/2016/02/solved-examples-b2.html
http://blogformathematics.blogspot.com/2016/02/worksheet-b2.html