X-coordinate of vertex (or axis of symmetry) of a quadratic function <span><span>f<span>(x)</span></span>=a<span>x2</span>+bx+c</span><span> is given as:</span> <span>x=−<span>b<span>2a</span></span>=−<span>b<span>12</span></span>=−2<span>b-2b = 6 --> <span>b=<span>6<span>−2</span></span>=−<span>3 </span></span><span>b = -3</span> </span></span>
