# Math Help - Testing LaTeX

1. I thought i had to write \x^2 when typing an exponent guess i dont.

2. $\sum=mc^2$

$a^2+b^2=c^2$

$\frac{\pi^2-7}{3x+2}=28$

$\sqrt{5x^3-2x+4}$

$\left(\begin{array}{cccc}1&0&1&1\\0&1&1&1\\1&1&1&1 \\0&1&0&1\end{array}\right)$

3. Originally Posted by OzzMan
How do i have it so theres spaces inbetween my entries, or have them on different levels. I tried hitting enter when im typing the code in but it did nothing.
if you want spaces then use \, or ~

4. How do i make a 3x3 matrix

5. Originally Posted by OzzMan
How do i make a 3x3 matrix
there are many ways to do that. i always use the "array function" --if that's what it's called.

the code \left( \begin{array}{ccc} a & b & c \\ d & e & f \\ g & h & i \end{array} \right)

yields

$\left( \begin{array}{ccc} a & b & c \\ d & e & f \\ g & h & i \end{array} \right)$

also see post #5 here

6. Oh so every time i want to increase the size i add a c to the code. I see.

7. $\frac{8x^2-3x+5}{7x+4}=4x^3$

This is awesome

$\sqrt[3]{27x^3}\Longrightarrow3x$

$(3x-8y)(2x^2-4xy+14y^2)\Longrightarrow$ Anyone know if I solved this correctly?

My answer is $6x^3+4x^2y+74xy^2-112y^3$

Wow I'm bored

Heres another question:

$\left(\begin{array}{ccc}5&3&9\\3&0&7\\8&2&1\end{ar ray}\right)$ Solve the following matrix without a calculator

The steps i took to get my answer were as follows:

$5\left(\begin{array}{cc}0&7\\2&1\end{array}\right)$
$-3\left(\begin{array}{cc}3&7\\8&1\end{array}\right)$
$9\left(\begin{array}{cc}3&0\\8&2\end{array}\right)$

From there i got 5(-14)-3(-53)+9(6) Which led me to my answer of 143

Not positive if this is right. If it is not correct, can you post the steps you took to get the answer so I can see what I did wrong. Thanks.

8. Originally Posted by OzzMan
Oh so every time i want to increase the size i add a c to the code. I see.
well, technically no. the number of c's tells you the number of columns, however, the letter c actually means to center align here. i could have put rrr (right align all columns) or lll (left align all columns)

9. Originally Posted by OzzMan
From there i got 5(-14)-3(-53)+9(6) Which led me to my answer of 143

Not positive if this is right. If it is not correct, can you post the steps you took to get the answer so I can see what I did wrong. Thanks.
you are correct, that is the determinant. you used the cofactor expansion method here, one of several methods to finding determinants of nxn matrices. there is another method you could have used to confirm your answer (it only works for 3x3 matrices) however, it's hard to describe the process in words, so just wait until your professor teaches you

10. Originally Posted by Jhevon
you are correct, that is the determinant. you used the cofactor expansion method here, one of several methods to finding determinants of nxn matrices. there is another method you could have used to confirm your answer (it only works for 3x3 matrices) however, it's hard to describe the process in words, so just wait until your professor teaches you
Frankly I see no reason to learn any method for computing determinants other than the cofactor method. In order to do the 3 x 3 formula (the one where you put numbers beside the matrix and multiply down the columns) or any other you essentially have to learn a formula. And it doesn't generalize well to larger matrices. I prefer to learn the general method and leave it at that.

-Dan

11. Mmm... I'd ask to a Moderator or someone else if he may move the off-topic posts.

The aim of this topic, it's about testing LaTeX codes, and no solving problems about Matrix - Linear Algebra and all that stuff.

12. Originally Posted by topsquark
Frankly I see no reason to learn any method for computing determinants other than the cofactor method. In order to do the 3 x 3 formula (the one where you put numbers beside the matrix and multiply down the columns) or any other you essentially have to learn a formula. And it doesn't generalize well to larger matrices. I prefer to learn the general method and leave it at that.

-Dan
i agree

but i'm always one for knowing several ways to do the same thing.

Originally Posted by Krizalid
Mmm... I'd ask to a Moderator or someone else if he may move the off-topic posts.

The aim of this topic, it's about testing LaTeX codes, and no solving problems about Matrix - Linear Algebra and all that stuff.
i concur

13. $frac {1}{x}$

14. Originally Posted by james jarvis
testing.

[tex]
frac {1}{x}
[\math]
Remember its \frac{1}{x}

15. Originally Posted by james jarvis
$\ frac {1}{x}$
What are you doing lad? Dont put spaces between \ and frac and the brackets.

Simply: \frac{1}{x}

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