## anonymous 5 years ago The line of symmetry of the parabola whose equation is y = ax^2 - 4x + 3 is x = -2. What is the value of "a"? a) -2 b) -1 c) -1/2

The line of symmetry occurs at that line of x where the parabola is a minimum (or maximum). The x-value at which a parabola is minimal (or maximal) is $x=\frac{-b}{2a}$for a parabola with equation, $y=ax^2+bx+c$ You have the following,$x=-2, b=-4$Solving for a gives you$a=\frac{-b}{2x}=\frac{-(-4)}{2(-2)}=-1$which is answer (b).