SOLUTION: Please help, solve by completing square x^2-4x-1=0

Algebra.Com
Question 266090: Please help, solve by completing square
x^2-4x-1=0

Answer by dabanfield(803)   (Show Source): You can put this solution on YOUR website!
x^2-4x-1=0
Rewrite as:
x^2 - 4x = 1
We need to add a constant to both sides so that the left side becomes a perfect suqare of the form (x+a)^2.
Since the middle term is -4x we know that the constant needs to be -4/2 = -2 which when squared is (-2)^2 = 4. So we add 4 to both sides of the equation above:
x^2 - 4x + 4 = 1 + 4
(x-2)^ = 5
Taking the square root of both sides above we have x-2 = sqrt(5) or x-2 = -sqrt(5) so
x = 2+sqrt(5) or x = 2-sqrt(5)

RELATED QUESTIONS

Please help Solve the quadratic equation by completing the square. {{{ x^2-4x-6=0... (answered by ikleyn,ewatrrr,MathTherapy)
Solve: x^2 - 4x - 1=0 by completing the... (answered by jim_thompson5910)
Please help me solve this. Solve by completing the square X^2 - 4X - 12 = 0 THANK... (answered by sudhanshu_kmr)
please help?? it says solve by completing the square: x^2+8x+3=0 x^2+4x+1=0... (answered by stanbon,vleith)
can you please help me solve by completing the square of: (((... (answered by Mathtut)
can you please help me solve by completing the square ((( x^2-x-1=0... (answered by solver91311)
can you please help me solve by completing the square of ((( x^2-x-1=0... (answered by josmiceli)
Please help to solve this equation by completing the square: 3x^2 - x - 1 =... (answered by josmiceli)
solve by completing the square?... (answered by sdmmadam@yahoo.com)