Well if y represents the vertical distance of the ball then you want to solve the equation for when y is 0, since 0 would represent the ball being on the ground. So substitute 0 in for y and solve the equation.
0 = - 0.001x^2 + 0.3x
we have a common factor of x in both terms so we can take that out.
0 = x(-0.001x + 0.3)
Zero product property tells us that we can set both of those products equal to zero and solve
0 = x
0 = -0.001x + 0.3
our first answer is x = 0 is obvious bc thats when the ball starts before you hit it, means it traveled 0.
solving the second equation gives us x = 300
so the ball traveled 300 "yards" I suppose your problem starts, which is impossible, but no matter thats the answer :-)
