The graph of $y = ax^2 + bx + c$ has an axis of symmetry of $x = -1.$ If $a = 2,$ then find $b.$
The x coordinate of the vertex = -1 = -b / (2a)
So
-b / ( 2 * 2) = -1
-b / 4 = -1
b/4 = 1
b = 4