KEAM 2011 Math Paper

A quadratic equation x2+bx−16=0 have integer roots, when it has following conditions.
I. b must be even integer.
II. its discriminant is a perfect square of an even number.
So, D=b2+4⋅16=b2+64
Here, 0 and 6 only the even integers value of b, on which the discriminant of given quadratic equation have perfect square of an even number.
So, the number of integral values of b is 2 .