# What is b in this quadratic equation 3x^2 - 15 = 8x?

May 10, 2018

$b = - 8$

#### Explanation:

Given: $3 {x}^{2} - 15 = 8 x$

Subtract $8 x$ from both sides.

$3 {x}^{2} \textcolor{w h i t e}{\text{.}} \textcolor{red}{- 8} x - 15 = 0$
$a {x}^{2} \textcolor{w h i t e}{\text{.")ubrace(+color(red)(b))x+color(white)("d}} c = 0$
$\textcolor{w h i t e}{\text{.d..d}} \downarrow$
$\textcolor{w h i t e}{\text{dd")obrace(+(color(red)(-8)))color(white)("d}} \to - 8$