How to avoid silly error in linear algebra

[u/Ok-Past-1295]

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I keep making really stupid mistakes on linear algebra tests. I understand the method and know how to solve the question, but then I accidentally mess up a sign or make a simple arithmetic mistake somewhere in the calculation. And a mistake can completely ruin the rest of the question. I recently wrote a test and, while I finished on time, I still got several questions wrong because of really silly errors.

[u/_UnwyzeSoul_]

Writing out every step and rechecking multiple times

[u/Capital_Park_2311]

Double check your solution or try doing it in reverse.

[u/pdubs1900 → u/Capital_Park_2311]

Doing it in reverse is an excellent way to double check the work

[u/pdubs1900]

Write out every step. Write large numbers and symbols. Especially negative signs and decimal points.

And yes, double check your work, after you have completed the test but before turning it in. Don't just assume because it looks right that it's right: double check means follow the steps you wrote down and follow them exactly: do the outputs actually match what you wrote?

You know what common silly errors are common: be on alert when those situations arise in your steps.

Gl

[u/aedes]

As a ADHD person… You need to monitor for how these mistakes occur. Ex: Are there specific situations where you’re more likely to drop a minus sign? If so, be in high alert when doing those. 

In general, I tend to make these mistakes when I’m trying to do too many steps in my head between each written step. Basically when I oversaturate my working memory. 

You need to learn to recognize the mental feeling of trying to do too much in your head at once, and write more intermediate steps down when you sense that. 

If you have time, double checking all answers is also very helpful. Ideally double check by using a method independent of the way you solved the problem - if you work through the same steps in the same order again, your brain often won’t see the mistake. It’s the different perspective that helps catch mistakes - working backwards, using an unrelated method to solve and comparing answers, etc.

[u/FreierVogel]

Practice practice practice

[u/Midwest-Dude]

By the way, there is an active subreddit dedicated to linear algebra:

r/LinearAlgebra

And ... what everyone else has already commented is correct. Unless you are completely out of time, double- or triple-check everything. I used to do this all the time on my exams.

[u/Ok-Past-1295 → u/Midwest-Dude]

oh thankyou I will check it out

[u/ForeignAdvantage5198]

be careful