The graph of $y = ax^2 + bx + c$ has an axis of symmetry of $x = -1.$ If $a = 2,$ then find $b.$

omgitsrne Feb 12, 2024

#1**+1 **

The vertex of a parabola lies on the axis of symmetry. Remember that the x-coordinate of the vertex (and the equation of the axis of symmetry) is **x = -b/2a**.

We know in this problem that -b/2a = x = -1. We also know a = 2, so substituting we get -b/4 = -1, -b = -4, and __ b = 4__.

proyaop Feb 12, 2024