1. ## Quick Simplify

Ok so im trying to find the roots of $(x+2)(4x^2-8x-3)$

I went and used the Quadratic Formula to get

$x = \frac{8 \pm \sqrt{(-8)^2 - 4(4)(-3)}}{8}$

$x = \frac{8 \pm \sqrt{112}}{8}$

Now this is where i get stuck
I want to leave it as a radical*

2. ## Simplifying…

Use the fact that 112 = 16*7

--Kevin C.

3. Originally Posted by TwistedOne151
Use the fact that 112 = 16*7

--Kevin C.
$x = \frac{8 \pm 4\sqrt{7}}{8}$

It can be simplified more though,

my text says $x = \frac{2 \pm 2\sqrt{7}}{2}$ but how//

4. ## Simplifying…

Note that 8=4*2, so $x = \frac{8 \pm 4\sqrt{7}}{8} = \frac{4 \cdot 2 \pm 4\sqrt{7}}{4 \cdot 2}= \frac{4 (2 \pm \sqrt{7})}{4 \cdot 2}$ and we cancel the 4s in the numerator and denominator to get $x = \frac{2 \pm \sqrt{7}}{2}$.

--Kevin C.