What are the pros and cons of completing the square as a way to solve quadradic equations?

1. 👍 0
2. 👎 0
3. 👁 259
1. Completing the square is not the easiest way to solve quadratic equations; its strength lies in the fact that the process is repetitive and predictable.

Here is the best news: completing the square ALWAYS (SAY ALWAYS) will work, unlike the factoring method, which of course, requires that the trinomial be factorable.

1. 👍 0
2. 👎 0
posted by Guido
2. I find the quadratic equation
x = [-b +/- sqrt(b^2-4ac)]/2a
the easiest to use, unless a way of factoring is obvious. It is derived by completing the square, after all. It tells you the number of real roots right away (from the value of b^2 - 4ac). The hard part is memorizing it, but after a while it becomes routine.

1. 👍 0
2. 👎 0
posted by drwls
3. I use the following rule:
If the coefficient of the squared term is 1 and the coefficient of the first degree term is even, then I would use completing the square, otherwise just use the quadratic formula

e.g.

x^2 - 12x -5 = 0
x^2 - 12x = 5
x^2 - 12x + 36 = -5 + 36
(x-6)^2 = 31

x = 6 ± √31

In this case this method is actually faster and easier than using the formula, since the formula answer has to be broken down to lowest terms.

1. 👍 0
2. 👎 0
posted by Reiny
4. Thank you.

1. 👍 0
2. 👎 0
5. Cool rule, thank you.

1. 👍 0
2. 👎 0
6. Thank you for the example.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Algebra Question

Quadratic equations can be solved by graphing, using the quadrat completing the square, and factoring. What are the pros and cons these methods? When might each method be most appropriate?

asked by pj on January 29, 2009
2. ### algebra

Quadratic equations can be solved by graphing,using the quadratic formula, completing the square, and factoring. What are the pros and cons of the methods. when would each be appropriate?

asked by debby on February 7, 2012
3. ### Algebra

I understand that systems of equations can be solved by graphing or by using substitution or elimination. But I cannot think of any pros or cons so... What are pros and cons of each method?

asked by Lynn on June 10, 2010
4. ### History

I have written a paper on John D. Rockefeller and now I am stuck could someone please help me? What were the pros and cons of big business in the 19th Century? Do these pros and cons still exist today? Thanks so much for the help.

asked by B.B on December 20, 2009
5. ### ALGEBRA

Quadratic equations can be solved by graphing, using the quadratic formula, completing the square, and factoring. What are the pros and cons of each of these methods? When might each method be most appropriate? Which method do you

6. ### ALGEBRA--MAT 117

Quadratic equations can be solved by graphing, using the quadratic formula, completing the square, and factoring. What are the pros and cons of each of these methods? When might each method be most appropriate? Which method do you

7. ### math 117

Quadratic equations may be solved by graphing, using the quadratic formula, completing the square, and factoring. What are the pros and cons of each of these methods? When might each method be most appropriate? Which method do you

asked by Anonymous on December 5, 2011
8. ### Mat/117 DQ2

Quadratic equations may be solved by graphing, using the quadratic formula, completing the square, and factoring. What are the pros and cons of each of these methods? Please provide examples. When might each method be most

asked by Rose on February 27, 2012
9. ### Math (Algebra)

I sent my professor asked the pros and cons of each method, I answered with this; When graphing; pros are that graphing gives you a picture of what the solution is. Cons would be is that graphing is not always accurate and it is

asked by Lynn on June 23, 2010
10. ### Family and Consumer Sciences

I am doing a sewing project. I need to decide what project to do. I have four choices. I need find pros and cons. I am having trouble finding the right format for these pros and cons. they need to be written like " I chose the

asked by Fluffy_Bunny on November 29, 2016

More Similar Questions