A quadratic equation is written in four equivalent forms below.

I. y = (x - 4)(x + 6)
II. y = x(x - 4) + 6(x - 4)
III. y = (x + 1)2 - 25
IV. y = x2 + 2x - 24

Which of the forms shown above would be the most useful if attempting to find the y-intercept of the quadratic equation?