Solve for x: 2x^2 - 4x - 14 = 0
Explain the steps??

Question

Solve for x: 2x^2 - 4x - 14 = 0 
Explain the steps??

phi · Answer

when you have time, this explains how http://www.khanacademy.org/math/trigonometry/polynomial_and_rational/quad_formula_tutorial/v/using-the-quadratic-formula

anonymous · Answer

2x^2 = 2*2 = 4x

anonymous · Answer

I'm using the quadratic formula; now I'm at x=4+/- sqrt 4240/4, what do I do now

anonymous · Answer

240****

anonymous · Answer

4x-4x-14=0

anonymous · Answer

tell me is this is right then...
2x2-4x-14=0
4x-4x-14=0
but then no solution because it's
0x-14=0???

anonymous · Answer

0x-14=0
so then add 14
0x = 14
So x would be undefined

anonymous · Answer

okay thank you

anonymous · Answer

Did that help?

phi · Answer

$$2x^2-4x-14=0$$
a= 2, b= -4,  c= -14
use the quadratic formula
$$ x= \frac{1}{2a} \left( -b ± \sqrt{b^2 - 4 ac}\right) $$
$$ x= \frac{1}{2\cdot 2} \left( -(-4) ± \sqrt{(-4)^2 - 4 \cdot 2 \cdot -14}\right) 
\x= \frac{1}{4}\left( 4 ± \sqrt{16 +112}\right) \
x= \frac{1}{4}\left( 4 ± \sqrt{128}\right) 
$$

can you finish ?