# Science talk:Math Exam Resources/Courses/MATH221/December 2008/Question 03 (a)

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Thread title | Replies | Last modified |
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Solution requires more details | 2 | 04:55, 8 February 2015 |

In the solution you say *there will be no terms containing cubic (or higher) powers* - why is that?
If the statement above is true, how do you get to the next line?
What do you mean by *If the above holds for every choice...*? Does it hold, or do we still need to show that it holds?
I would like to see the calculation required to get the correct sign.

If there is something clever here that I'm missing, I suggest this moves to solution 2. The first (supposedly most straight-forward) solution should be to go ahead and subtract the first row from the other two, and factor the determinant of the resulting 2x2 matrix.

You are absolutely right, on hindsight it's not a clean/clear argument at all (I was a little too eager in avoiding calculations!), and certainly the most straightforward solution is the one above. In view of this, I am in agreement and will remove and replace with the latter as you suggest.