Posted by **debby** on Tuesday, February 7, 2012 at 6:53pm.

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?

- algebra -
**Reiny**, Tuesday, February 7, 2012 at 7:09pm
graphing gives you a ball-park answer, even showing if there are any real solutions

If the equation starts with x^2 and the middle term is even, I ALWAYS use completing the square, it is faster than using the formula and gives you the reduced answer if it is irrational

I often do a quick calculation of the discriminant

b^2 - 4ac on my calculator.

If that answer is a perfect square, then my quadratic will factor,

If the coefficients are single digits I usually look for factors, takes just a few seconds

If the numbers are two digits or "unruly" I just go for the formula way.

This used to be a problem in the past but with today's calculators the difficulty becomes a mute point.

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