# What is the axis of symmetry and vertex for the graph y = 3(x)^(2) - 7 x - 8?

Mar 16, 2016

Show you a really cool trick for this
x_("vertex")=7/6=" axis of symmetry"
I will let you find ${y}_{\text{vertex}}$

#### Explanation:

Given:$\text{ } y = 3 {x}^{2} - 7 x - 8$

Factor out the 3 for the ${x}^{2} \text{ and the "x" terms}$

$\text{ } y = 3 \left({x}^{2} - \frac{7}{3} x\right) - 8$

Now apply $\left(- \frac{1}{2}\right) \times - \frac{7}{3} = + \frac{7}{6}$

${x}_{\text{vertex}} = \frac{7}{6}$

Axis of symmetry$\to x = \frac{7}{6}$

Just substitute $x = \frac{7}{6}$ in the original equation to find ${y}_{\text{vertex}}$