1. The problem statement, all variables and given/known data When the parabola y=x^2-a(x+1)+3 intersects the x-axis at one point then a=_ or =_. 2. Relevant equations The equation of parabola y^2=4px,x^2=4py depending on the orientation 3. The attempt at a solution Since the parabola meets the x axis once, I assume that to be the vertex.I try to rearrange the function into an appropriate form but I get stuck here. y=x^2-ax-a+3 The equation already has two unknowns and hell breaks lose when I try to complete the square.