Discover Questions

If space is a vacuum and a wave is a disturbance of a medium causing a moving force,so how can a gravity wave exist with no medium? Does it take time to produce energy? How do I find the vertex of y=-x^2+4x-2? Determine if this graph is even, odd, or neither. f(x)=x^3+x^2+4.? Hypotenuse of a right triangle?