x2 – 4ax + 4a2 – b2 = 0
Using splitting middle term, the middle term of the general equation 
is divided in two such values that:
Product = a.c
For the given equation 
= 
= 
And either of their sum or difference = b
= 
Thus the two terms are 
Sum = 
= 
= 
Product = 
using 
= 
= 
x[x-(2a + b)]-(2a-b)[x-(2a + b)] = 0
[x-(2a-b)][x-(2a + b)] = 0
[x-(2a-b)] = 0 or [x-(2a + b)] = 0
x = (2a-b) or x = (2a + b)
Hence roots of equation are x = (2a - b) or x = (2a + b)
55