Question

What is the value of b2 - 4ac for the following equation? 2x 2 - 2x - 1 = 0

Answer 1

To figure that out we will need to know the quadratic formula which is: 
$x=\frac{ -b \pm \sqrt{b^2-4ac} }{ 2a }$

Since we only want to know the square root part we will solve only for this part: 
$\sqrt{b^2-4ac}$

Now we need to list our values (a,b,c) 
To determine which number belongs to which letter we use the standered form equation which is :
$ax^2+bx+c$

And next part is super easy! We simply match up the numbers to the letters. We have: 
a=2
b=-2
c=-1 
Next we plug in the given info into the square root:
$\sqrt{(-2)^2-4(2)(-1)}$
Now we solve: 
$\sqrt{(4-4(2)(-1)}$
$\sqrt{(4-8(-1)}$
$\sqrt{(4-(-8)}$
$\sqrt{(12)}$
$\sqrt{(12)}$
$\sqrt{(12)}=3.46$
Final answer: 3.46

Answer 2

Answer:

12.

Step-by-step explanation:

$2x^{2} -2x-1=0$

a= 2, b= -2 and c=-1. Then,

$b^{2}-4ac = (-2)^{2}-4(2)(-1) = 4+8 = 12.$