Error prune thinking.

I can't phrase my problem well, so I have to give an example here.

I was doing this algebra problem

1 Write down the 3 by 3 matrices that produce these elimination steps:
(a) E21 subtracts 5 times row 1 from row 2.
(b) E32 subtracts -7 times row 2 from row 3.
(c) P exchanges rows 1 and 2, then rows 2 and 3.

The answer to question (a) is straightforward

| 1 0 0 |
| -5 1 0 |
| 0 0 1 |

Now please pay attention to question (b)
The correct answer should be
| 1 0 0 |
| 0 1 0 |
| 0 7 1 |

In principle if I could do question (a), question (b) is just the same concept.
But I gave the wrong answer, my answer was
| 1 0 0 |
| 0 1 0 |
| 0 -7 1 |

I made this mistake is because I didn't notice the minus sign before 7.
I saw it ,but it didn't register during problem solving procedure.
Had the question be phrased, add 7 times row 2 to row 3, I would've given the correct answer.
I understand the concept and procedure to answer the question, but made a mistake.
I often make this kind of mistakes, my parents always yell at me when I do that, but I continue make this kind of mistakes.
Could someone please explain to me, why am I make such errors? do other people also make mistakes like I do? What can I do so I stop or make fewer mistakes of this kind?

We all make errors like that.. we just don't register all the little details properly at times.

I think the real issue though is the pressure you're being put under by your parents.. you shouldn't be getting yelled at for making a human error.

Something that might help a little is to say the problem out-loud instead of silently reading it.. verbalising it should make your brain process it a little better, without skipping over the small details.
Plenty of people quietly read things like that outloud to themselves.. clearly you won't be able to do it at more than the level of the quietest whisper in an exam situation, but doing this should really help, and will train your brain to pause and process each detail of the problem you're looking at.

Do your parents yell a lot though? how do they treat you in general?

seabreezeblue wrote:We all make errors like that.. we just don't register all the little details properly at times.

I think the real issue though is the pressure you're being put under by your parents.. you shouldn't be getting yelled at for making a human error.

Something that might help a little is to say the problem out-loud instead of silently reading it.. verbalising it should make your brain process it a little better, without skipping over the small details.
Plenty of people quietly read things like that outloud to themselves.. clearly you won't be able to do it at more than the level of the quietest whisper in an exam situation, but doing this should really help, and will train your brain to pause and process each detail of the problem you're looking at.

Do your parents yell a lot though? how do they treat you in general?

Thanks for the suggestions.
Sorry I made grammar mistakes in my first post, all things I said were in the past. I am too old to take any exams now. I am learning math now to prevent alzeimer's disease, also because I couldn't do it when I was younger when I got mental illness.

I am curious because I know some people achieve almost perfect scores in SAT or similar tests. And there are certain jobs that demand accuracies, such as cashier，accountant or surgeons.
My dad told me that posts dealing with money or have responsibilities don't fit me because I made a lot of mistakes. But my father wanted me to be a physician. I didn't want to be a physician though, because that job has a few risks, including wrong diagnosis causing suffering of a patient and the risk of contracting infectious disease from work. I wonder if people with those kind of jobs are different than others. I haven't heard of cashiers or accountants made a lot of human errors though.

Before I had mental illness, when I was younger, my test scores were at least in top 10%, even I was error prune. But now I am at the bottom. Why my father had such low opinions about me, he got very angry when I entered a very good university because he predicted I would get bad grades due to the university's high standards. And why in the end, he was proved to be right that I was indeed a failure?