Using the splitting middle term - the middle term of the general equation is divided in two such values that:

Product = a.c

For the given equation a = 9; b = 6; c = 1

= 9.1 = 9

And either of their sum or difference = b

= 6

Thus the two terms are 3 and 3

Sum = 3 + 3 = 6

Product = 3.3 = 9

Hence the equation has repeated roots