Are these right? (Determinants)

$\displaystyle \left|\begin{array}{ccc}a_1 & b_1 & c_1 \\ a_2 & b_2 & c_2 \\ a_3 & b_3 & c_3 \end{array}\right|$

Hello all! I'd like to check these as I'm not very confident that I got them right, and I'd really appreciate your input, especially as I've scrambled my brains with trilingual madness! (Rofl) So much fun :D

Anywho here's the questions with my answers, are they right?

Evaluate the following determinants.

$\displaystyle \left|\begin{array}{ccc}-5 & 0 & 0 \\ 0 & 3 & -2 \\ 0 & 4 & 0 \end{array}\right|$

and

$\displaystyle 3\left|\begin{array}{ccc}-2 & -1 & 0 \\ -3 & 5 & -2 \\ 0 & 8 & -1 \end{array}\right|$

*My answers;*

$\displaystyle \left|\begin{array}{ccc}5 & 0 & 0 \\ 0 & 3 & -2 \\ 0 & 4 & 0 \end{array}\right|$

$\displaystyle =(5)(3)+(4)+(-2)-(3)-(-5)(4)(-2)=-56$

and

$\displaystyle 3\left|\begin{array}{ccc}-2 & -1 & 0 \\ -3 & 5 & -2 \\ 0 & 8 & -1 \end{array}\right|$

$\displaystyle =3(-2\left|\begin{array}{cc}5 & -2 \\ 8 & -1 \end{array}\right|$$\displaystyle +1\left|\begin{array}{cc}-3 & -2 \\ 0 & -1 \end{array}\right|$$\displaystyle +0\left|\begin{array}{cc}-3 & 5 \\ 0 & 8 \end{array}\right|)$

$\displaystyle =3(-22 + 3 + 0) = -57$

And one more question;

*Expand by minors*

$\displaystyle \left|\begin{array}{ccc}3 & 4 & -2 \\ 6 & 4 & 3 \\ 0 & 4 & 2 \end{array}\right|$

This question *really *bothers me considering that supposedly it doesn't matter which row or column you expand- you're supposed to get the same answer everytime, I'm getting a different answer each time.

Example, expanding the first row;

$\displaystyle =3\left|\begin{array}{cc}4 & 3 \\ 4 & 2 \end{array}\right|$$\displaystyle -4\left|\begin{array}{cc}6 & 3 \\ 0 & 2 \end{array}\right|$$\displaystyle -2\left|\begin{array}{cc}6 & 4 \\ 0 & 4 \end{array}\right|$

$\displaystyle =3(8-12)-4(12-0)-2(24-0)=-108$

And if I expand the middle column;

Example, expanding the first row;

$\displaystyle =-4\left|\begin{array}{cc}6 & 3 \\ 0 & 2 \end{array}\right|$$\displaystyle +4\left|\begin{array}{cc}3 & -2 \\ 0 & 2 \end{array}\right|$$\displaystyle -4\left|\begin{array}{cc}3 & -2 \\ 6 & 3 \end{array}\right|$

$\displaystyle =-4(12-0)+4(6-0)-4(9-12)=-12$

So... what am I doing wrong? D:

Thanks in advance for any help