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 = 1, b = 6, c = 5

= 1.5 = 5

And either of their sum or difference = b

= 6

Thus the two terms are 1 and 5

Sum = 5 + 1 = 6

Product = 5.1 = 5

x(x + 1) + 5(x + 1) = 0

(x + 1)(x + 5) = 0

(x + 1) = 0 or (x + 5) = 0

x = -1, x = -5

Roots of equation are - 1, - 5