You are Here: Home >< Maths

# Matrix help

Announcements Posted on
TSR's new app is coming! Sign up here to try it first >> 17-10-2016
1. I just can't seem to work out how to solve this :/ . Anyone care to solve this problem and explain?

Thanks!
Attached Images

2. (Original post by abccba120)
I just can't seem to work out how to solve this :/ . Anyone care to solve this problem and explain?

Thanks!
Have you found in terms of t?
3. (Original post by B_9710)
Have you found in terms of t?
No, is that what I need to do? How do I go about finding in terms of t ..
4. (Original post by abccba120)
No, is that what I need to do? How do I go about finding in terms of t ..
Just do matrix multiplication in the normal way (A*A = A^2, then A*A^2 = A^3)
5. (Original post by abccba120)
...
Perhaps worth mentioning, if you've covered determinants, that

So,
and thus assuming your matrix is real

.............(1)

You can use this to check your result.

In itself though, it is insufficient to find the value of t, since (1) is satisified by two values of t, only one of which yields the identity matrix when cubed.
6. (Original post by ghostwalker)
Perhaps worth mentioning, if you've covered determinants, that

So,
and thus assuming your matrix is real

.............(1)

You can use this to check your result.

In itself though, it is insufficient to find the value of t, since (1) is satisified by two values of t, only one of which yields the identity matrix when cubed.
The determinant wouldn't be of much use here because the determinant being 1 only indicates that there is no change in volume nor reflection. It says nothing about the rotation that the original matrix may assume, and the identity matrix is very specific that there is no rotation, reflection or sheering/stretching in any directions.
7. (Original post by RDKGames)
The determinant wouldn't be of much use here because the determinant being 1 only indicates that there is no change in volume nor reflection. It says nothing about the rotation that the original matrix may assume, and the identity matrix is very specific that there is no rotation, reflection or sheering/stretching in any directions.
I do get the impression that you didn't actually read my post - I suggested it as a way to check an answer, not a means to derive it.
8. (Original post by ghostwalker)
I do get the impression that you didn't actually read my post - I suggested it as a way to check an answer, not a means to derive it.
I did. I'm simply giving the geometrical interpretation for the OP of what is happening with your method.
9. (Original post by RDKGames)
I did. I'm simply giving the geometrical interpretation for the OP of what is happening with your method.
Mate, Ghostwalker is a big boy round these ends, don't f**k with him. He's been doing maths before you were even born.
10. (Original post by Ano123)
Mate, Ghostwalker is a big boy round these ends, don't f**k with him. He's been doing maths before you were even born.
He must be easily triggered if that's considered 'f**cking' with him.
11. (Original post by RDKGames)
He must be easily triggered if that's considered 'f**cking' with him.
Although you clearly didn't read his post. He never said it was to find the answer, just check it.
12. (Original post by alow)
Although you clearly didn't read his post. He never said it was to find the answer, just check it.
I just wanted to put out some sort of geometrical interpretation linking to the original matrix and why it wouldn't work. Since he mentioned determinants it was suitable to respond to that and I might've mis-worded my response in the process, he's not wrong and I understood what he said. No need to be picky, let's just appreciate the fact that we're helping OP.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: August 21, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams