Integral value(s) of a such that the quadratic equation `x^(2)+ax+a+1=0` has integral roots is/are

The number of integral values of 'a' for which the quadratic equation x^(2)+(a+19)x+19a+1=0 has integral roots,are

The number of integral values of a for which the quadratic equation (x+a)(x+1991)+1=0 has integral roots are a.3 b.0 c.1 d.2

Find the value(s) of k so that,the quadratic equation x^(2)-4kx+k=0 has equal roots.

Number of possible value(s) of integer 'a' for which the quadratic equation x^(2) + ax + 16 = 0 has integral roots, is

The quadratic equation ax^(2)+bx+c=0 has real roots if:

The quadratic equation ax^(2) - 4ax + 2a + 1 = 0 has repeated roots, if a =

Value(s) of k for which the quadratic equation 2x^(2)-kx+k=0 has equal roots is/are