SOLUTION: Solve the quadratic equation by completing the square: 3x^2+6x-4=0

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Question 169929: Solve the quadratic equation by completing the square:
3x^2+6x-4=0

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Start with the right side of the equation.


Factor out the coefficient . This step is very important: the coefficient must be equal to 1.


Take half of the coefficient to get . In other words, .


Now square to get . In other words,


Now add and subtract inside the parenthesis. Make sure to place this after the "x" term. Notice how . So the expression is not changed.


Group the first three terms.


Factor to get .


Combine like terms.


Distribute.


Multiply.


So after completing the square, transforms to . So .


So is equivalent to .


----------------------------------------------------------


Start with the given equation.


Add to both sides.


Combine like terms.


Divide both sides by .


Take the square root of both sides.


or Break up the "plus/minus" to form two equations.


or Simplify the square root.


or Subtract from both sides.


or Combine the fractions.


--------------------------------------


Answer:


So the solutions are or .

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