Verified Answer :

poojaa195

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

botellok

Answer:

12.

Step-by-step explanation:

\(2x^{2} -2x-1=0\)

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

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

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