Theory:

The difference of squares of two expressions:
aba+b=a2b2
The product of the sum and difference of two expressions is equal to the difference of the squares of these expressions:
 
aba+b==aa+abbabb==a2+ababb2==a2b2
Application of the formula aba+b=a2b2
Example:
1) According to the formula:
 
x3x+3==x232==x29
 
Without the formula (multiplying a polynomial by a polynomial):
 
x3x+3==xx+x33x33==x2+3x3x9==x29
 
2) According to the formula:
 
4xy4x+y==4x2y2==16x2y2

Without the formula (multiplying a polynomial by a polynomial):
 
4xy4x+y==4x4x+4xyy4xyy==16x2+4xy4xyy2==16x2y2
 
3) According to the formula:
 
6z96z+9==6z292==36z281

Without the formula (multiplying a polynomial by a polynomial):
 
6z96z+9==6z6z+6z996z99==36z2+54z54z81==36z281