For a quadratic to have exactly one solution the discriminant must be zero. In this case that means we must have n^2 - 4*4*25 = 0, which means the positive value of n is 20.
For a quadratic to have exactly one solution the discriminant must be zero. In this case that means we must have n^2 - 4*4*25 = 0, which means the positive value of n is 20.