Question

please help me
3u-4v=9
5u-8v=4

Answer 1

\[{{3\ 9}\choose{5\ 4}}^{(45)}_{12}=-45+12=-33\]
\[{{3\ -4}\choose{5\ -8}}^{(-20)}_{-18}=20-18=2\]

v = -33/2 if i did that right

Answer 2

what is this method?

Answer 3

its systems of equations

Answer 4

something with determiates and Dv/D i think

Answer 5

algebra2

Answer 6

the answeres are (14,33/4) i just dont know how to get that

Answer 7

33/4 ?

Answer 8

yeah its a fraction

Answer 9

The second determinant is -4

Answer 10

8*3 = 24 .. not 18 lol

Answer 11

is this some of your variation of cramer's rule ?

Answer 12

its something like that; but I spent the winter break reading a linear algebra book to prep me for class

Answer 13

yes they are sets of equations but is that suppose to be the answere?

Answer 14

\[{{-4\ 9}\choose{-8\ 4}}^{(-72)}_{-16}=-16+72=56\]
and for this one we just negate the determinate for the denominator

56/4 = 14

Answer 15

lol, spare the kid :P

Answer 16

;)

-2(3u-4v=9)
5u-8v=4

-6u+8v=-18
5u-8v= 4
------------
-u = -14

u = 14

Answer 17

btw is this approach optimal for more equations? I mean this seems a bit convoluted for \( 2\times 2 \).

Answer 18

linear algebra is never optimal ...

Answer 19

hm I guess that's why we have numerical analysis ... ;)

Answer 20

\[{{3\ -4}\choose{5\ -8}}{u\choose v}={9\choose 4}\]
\[{u\choose v}={{3\ -4}\choose{5\ -8}}^{-1}{9\choose 4}\]

Answer 21

the one were you put the winky face was only the first 1 right ???

Answer 22

\[{{3\ -4}\choose{5\ -8}}^{-1}=\frac{1}{det}{{-8\ 4}\choose{-5\ 3}}\]
\[{{3\ -4}\choose{5\ -8}}^{-1}=\frac{1}{-4}{{-8\ 4}\choose{-5\ 3}}\]
\[{{3\ -4}\choose{5\ -8}}^{-1}={{2\ -1}\choose{5/4\ -3/4}}\]

such fun

Answer 23

When you got u= 14 you can put 42-4x=9 and solve for x.

Answer 24

should get 33/4

Answer 25

thanks bro !
really helped

Answer 26

i tried solving that last part but i got 42/13 ???

Answer 27

\[{u\choose v}={{2\ -1}\choose{5/4\ -3/4}}{9\choose 4}\]
\[{u\choose v}=9{2\choose5/4}^{18}_{45/4} +4{-1\choose -3/4}^{-4}_{-12/4}={{14}\choose{33/4}}\]

Answer 28

.... i needed the practice :)