Interpreting Quadratic Functions in Standard Form

When we have a quadratic function written in standard form, we can determine the $x\text{-}$coordinate of its vertex by using the formula $x=\text{-}\frac{b}{2a}.$ Let's consider our function. $$\begin{array}{c}y=4x^2+24x-7\iff y=4x^2+24x+(\text{-}7)\end{array}$$ We see that $a$ $=$ $4,$ $b$ $=$ $24,$ and $c$ $=$ $\text{-}7.$ By substituting these values into the corresponding formula, we will obtain the $x\text{-}$coordinate of the vertex. We can see that the error is the missing minus sign, so the correct $x\text{-}$coordinate of the vertex is $x=\text{-}3,$ and not $3.$