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=( -b \pm √(b^2-4ac) )/( 2a )`

Since we only want to know the square root part we will solve only for this part:

`√(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:

`√((-2)^2-4(2)(-1))`
Now we solve:

`√((4-4(2)(-1))`

`√((4-8(-1))`

`√((4-(-8))`

`√((12))`

`√((12))`

`√((12))=3.46`
Final answer: 3.46

Answer 2

12.

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.`