



 
Hi Ryan. You can find several examples of completing the square by using the Quick Search and typing in completing the square. I'm going to solve a similar problem: x^{2}  6x  39 = 0. Start by moving the scalar to the other side by negating it: Then take half the coefficient of the x term and square it: 6/2 = 3; (3)^{2} = 9. Add this to both sides: Then you have "completed the square" so the expression on the left is a perfect square. Its root is x  3, because 3 is onehalf the x term's coefficient (it is minus, because we have  6x). So we rewrite it as Now take the square root of both sides, remembering that a positive number on the right has both positive and negative roots. When you take the square root of a perfect square on the left side, the square root cancels with the squared: Then finish by isolating x by itself (move the 3 to the other side by negating) and simplifying the √48: Notice that this is two answers for x: Solution set = { 3  4√3, 3 + 4√3 }. On an exam, if I have time, I will check my answer as follows: Always try our search before posting a question  it saves you time. Cheers,  


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