Weegy: x=-1/4 User: Which of the quadratics has a graph with x-intercepts of 5 and -1? A) y = x2 - 4x - 5 B) y = x2 - 5x - 4 C) y = x2 + 4x - 5 D) y = 2x2 - 4x - 5 Weegy: One moment please. (More)

Weegy: The quadratic formula finds when, in a quadratic equation, y is equal to zero. This is sometimes called find the 'roots' of the equation. [ As to why you need to find these roots of quadratics, there will be times when you have to find when the y [ value is equal to zero. For example, consider an equation that models the projectile path of an object with displacement vs. time. If you wanted to find when that object has a displacement of zero (ie: when it hits the ground) you could use the quadratic formula to find the x value when y (the displacement) is zero. Hope that helps! ] ] (More)