# number bases, matrices, inverses, etc

#### Rohan

##### New member
Somene please explain to me, and show me how to do the following :

Convert the following numbers to denary (base 10):

1) 736_8 (that's 736, base-8)

2) DE1_16 (that's DE1, base-16)

3) 1100101_2 (that's 1100101, base 2)

Using the following matrix X:

. . .[..2 1..3 ]
. . .[ -1 3..0 ]
. . .[..2 4 -2 ]

4) Evaluate the matrix Y = X^t (that's X-transpose).
5) S = |X|

6) Using the following matrix A:

. . .[..1 3 0 ]
. . .[ -1 2 1 ]
. . .[..3 1 2 ]

Evaluate the polynomial Y = A^3 - 3A^2

7) Obtain the solution to the set of linear equations using Cramer's Rule.

. . .2x - 3y + 1z = 4
. . .1x + 1y + 1z = 3
. . .1x + 4y - 3z = -3

So is that then:

. . .| 2 -3..1..4 |
. . .| 1..1.. 1..3 |
. . .| 1.. 4 -3 -3 |

8) Use Gaussian elimination to find the inverse of the matrix Q, where Q is:

. . .[..1..2 1 ]
. . .[ -3 -4 1 ]
. . .[..4..6 4 ]
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Edited by stapel -- Reason for edit: fixing formatting

#### stapel

##### Super Moderator
Staff member
Rohan said:
Somene please explain to me, and show me how to do the following:
Have number bases, matrices, and determinants not been covered in class yet...? If not, why are you getting homework question on them...?

We cannot teach courses within this enviornment. If you're really needing lessons on these topics, please specify such, and we will try to find some links for you. But be advised that it make take a few weeks of study to get caught up on the background material, if you've really never seen this stuff at all.

Thank you.

Eliz.

#### Rohan

##### New member
Cover

Well thank you for all the help till now,

My postings are for anyone that want to help.

In fact it has not been covered, and I am in the process of trying to study it, doing a distance learning Degree in Information Technology, holding down a full time job and raising two children, that is where I am coming from.

Please show me the links I need, or point me in the right direction.

As for the question on Convert the following numbers to denary (base 10): --> sorted found a great website that cleared all of that up. here is the url http://www.golgotha.org.uk/useful/bases.html

If someone wants to check my answeres :
1) 448+24+6=478
2) 3328+176+1=3505
3) 1+0+4+0+0+32+64=101

Goodnight dark continent ...

Many Thanks,

R

#### stapel

##### Super Moderator
Staff member
1) To learn about number bases and how to convert between them, try here.

2) See (1),

3) See (1).

4) To see how to transpose a matrix, try here. (You won't be far wrong if you think of transposing as "tipping the matrix over", in a sense.)

5) Assuming that the bars mean that S is the determinant of the 3-by-3 matrix, you can learn how to find the determinant here.

6) This will take a few lessons. The cubing and squaring requires matrix multiplication. The "times 3" requires scalar multiplication. And the "minus" requires matrix addition.

7) To learn how to use Cramer's Rule (which requires determinants), try here.

8) To learn how to find the inverse of a matrix, try here.

This is a lot of material to absorb, and some of it is rather intricate, at least the first few times few. Give yourself some time to let it sink in.

Eliz.

#### Rohan

##### New member
Math+Problems=UR GR8

Eliz,

Thank you kindly,
I shall apply myself in mind and practice to the various sites you posted, and with effort, persistence and postings, I shall pass Management Science 01 this year, and learn something to boot. :lol:

R

#### Rohan

##### New member
Can someone check my answers PLZ

Thank you for your pm .... just read it toninght, and I checked it again you are correct it is multiply and not a variable.

Convert the following numbers to denary (base 10):

1) 736_8 (that's 736, base-8)
2) DE1_16 (that's DE1, base-16)

I have redone them, hope they are correct now, could you please check and let me know, if my answers are correct ? If it is not correct please tell me how you worked it out.

1) 3782
2) 3505

R

#### stapel

##### Super Moderator
Staff member
Rohan said:
Convert the following numbers to denary (base 10):

1) 736_8 (that's 736, base-8)
2) DE1_16 (that's DE1, base-16)

1) 3782
2) 3505
These are incorrect. In fact, your answer to (2) is the same one you gave in your first post...?

Eliz.

#### Rohan

##### New member
Uncle --- OK

Yes OK

this is my reasoning :

1) 6*8^0=6 + 3*8^1=24 + 3*9^2= 448 (ad all = 478)

2) 1*16^0=1 + E*16^1=224 + D*16^2= 3328 (ad all = 3553)

I found my mistake, would you ever stop putting me down !!! :evil: