Which equation has exactly one solution?
a. 4 - 12x - 9 = 0
b. 4 + 12x + 9 = 0
c. 4 - 6x - 9 = 0
c. 4 + 6x + 9 = 0
( show how you get the answer)

I would answer this by using the quadratic formula to figure out which equation only has one solution.
quadratic formula: (-b(+or-)√(b^2-(4ac)))/2a.
You find that the equation 4x²+12x+9=0 only has the root of x=-1.5.

Since the solution is where the parabola crosses the x-axis, you can also figure out which equation has only one solution by whether or not the axis of symmetry lands is a solution or not.  If the axis of symmetry is a solution, the function only has one solution (that being the vertex).  If the axis of symmetry is not a solution, the function has to have either two or no roots.  You can find the axis of symmetry by using the equation x=-b/2a.  Using that equation you can find that the equation 4x²+12x+9 has the axis of symmetry being at x=-1.5 which means that the vertex is (-1.5,0).  Since the equation 4x²+12x+9 has its vertex at (-1.5,0) and the vertex is the lowest or highest point of the function, that function only has one x-intercept meaning it only has 1 solution.  

I hope this helps.  Let me know in the comments if anything is unclear.

The answers are A and B

Explanation:

The First two answers talks about Vincent's movement between him and his new job which are related together.

On his first day on getting hired, he missed his way and had to ask for directions for the job he applied for, and his probably nervous, which makes him unsure of his confidence level and focus.

It is a stage directions from a play or drama