2x^2-10x-1=0, complete the square?

Question

List the missing value after completing the square.

Answer 1

2x² – 10x – 1 = 0

Separate variables and constants aside by adding 1 from each side 

2x² – 10x = 1

Here x² coefficient is 2, for perfect square make x² coefficient 1. 
Divide each side by 2

x² - 5x = ½

To change the expression into a perfect square trinomial add (half the x coefficient)² to each side of the expression.

Here x coefficient = -5. So, (half the x coefficient)² = (-5/2)²= 25/4

Add 25/4 to each side 
x² - 5x + 25/4 = ½ + 25/4

(x – 5/2) ²= 27/4

Take square root both sides 

x – 5/2 = ±√27/4

x – 5/2 = ±(3√3)/2

Add 5/2 to each side

x = 5/2 ±(3√3)/2

x = (5 ± 3√3) / 2