Question

Solve by completing the square 2x^2 -4x -4=0

A. 1+- √3
B.-1+- √3
C.-1+- 2√3
D.1 +- 2√3

Answer 1

divide every term by 2

and you get

\[x^2 -2x - 2 = 0\]

rewrite the equation as

\[x^2 -2x + ?= 2 +?\]

what do you need to add to both sides of the equation to get a perfect square on the left

Answer 2

2x^2 -4x -4=0
To complete the square:
Move the "non X" term to the right:
2x^2 -4x = 4
Divide the equation by the coefficient of X²
x² -2x = 2
take the coefficient of X which is -2
divide that by 2
which is -1
square that number
+1
then add it to both sides of the equation
x² - 2x +1 = 3
Take the square root of BOTH sides of the equation
x-1 = sqrt(3)

x = sqrt(3) +1
x = 1.732 +1

x = 2.732

sqrt(3) also = -1.732
x = -1.732 +1
x = -.732