Question

PLEASE HELP ASAP!!! medals will be given!
Solve: (if using calculator, make sure to write down what you are plugging in your calculator) write answers as fraction:

Answer 1

\[-x+2y-4z-5u=27\]
\[-2x-3y+3z-3u=9\]
\[5x-4y+2z-3u=5\]
\[-2x+4z-5u=29\]

Answer 2

This is a system of equations with 4 variables; you are going to want to use a calculator.

Answer 3

haha ok.. i dont exactly have one on me right now...but i hope you can help with that lol

Answer 4

Plug them into wolfram alpha. I'll try it.

Answer 5

BTW you are almost guaranteed to need a calculator for this class. Buy one.

Answer 6

i have one and i already took the class im just taking the final exam a year later haha...my calc is just not with me and i completely forgot how to do anything haha

Answer 7

http://www.wolframalpha.com/input/?i=%E2%88%92x%2B2y%E2%88%924z%E2%88%925u%3D27%2C+%E2%88%922x%E2%88%923y%2B3z%E2%88%923u%3D9%2C+5x%E2%88%924y%2B2z%E2%88%923u%3D5%2C+%E2%88%922x%2B4z%E2%88%925u%3D29

Answer 8

You shouldn't try to do anything with solving 4 equations/4 variables by hand. Too much work. Three equations is bad enough.

Answer 9

but its possible though, right?

Answer 10

Of course. Solving a million equations with a million variables by hand is possible, too. Probably not fun though.

Answer 11

my paper says my answer has to be in fractions....and i kinda hav to show work or atleast what i plugged into the calc..

Answer 12

The answers aren't in fractions, so your paper is stupid. You'd write that you plugged the four equations into your equation solver, and pressed solve.

Answer 13

LMFAO.. haha ok:)

Answer 14

I mean there's no way you "show work" from a calculator. You write in the equations, press solve. That's it.

Answer 15

theres another one thats.... two equations its.....

Answer 16

Two is doable by hand.

Answer 17

\[x-10y=24\]
\[12y=x ^{2}+2x-48\]

Answer 18

Use x−10y=24 to get either x = or y = and then substitute that into the second equation

Answer 19

eg. x−10y=24 gives x = 24+10y

replace every x in the second equation with (24+10y)

Answer 20

u could use matrices or cramer's rule...

@pinknabastak

Answer 21

@genius12 which is.....?

Answer 22

@agent0smith aso i put an equation in an equation...makes no sense

Answer 23

do you what determinants are? @pinknabastak

Answer 24

lol it makes sense. It's called substitution.

Since we have x = 24+10y

replace every x in this \[\Large 12y=x ^{2}+2x-48\]

Answer 25

haha nope:) @genius12

Answer 26

so then what..??

Answer 27

Plug it in. Show me what you get.

Answer 28

12y=(24+10y)^2+2(24+10y)-48

Answer 29

Good, now simplify/expand that all out, and solve for y.

Answer 30

nothing @pinknabastak its unrelated to this...

Answer 31

12y=48+40y

Answer 32

-48=28y

Answer 33

or -28y=48

Answer 34

\[\Large 12y=(24+10y)^2+2(24+10y)-48\]I'm not sure you expanded this correctly. You don't even have a y^2 term...

Answer 35

haha yea did i mention im bad at this?

Answer 36

Expand it out slowly, bit by bit.

Remember that (24+10y)^2 is the same as (24+10y)(24+10y)

Answer 37

yea i did that

Answer 38

Then show your work.

Answer 39

12y=24+10y+24+10y+48+20y-48
48's cross out
combine y's and 24's
12y=48+40y

Answer 40

(24+10y)(24+10y) do this part. Remember to use FOIL or whatever you're used to.

Answer 41

576 + 240y +240y + 100y

Answer 42

576 + 580y

Answer 43

10y*10y is 100y^2. But how come you did it completely different to what you did above?

Answer 44

576 + 240y +240y + 100y^2

Answer 45

ohh i forgot the y^2 part

Answer 46

so its 576 + 480y + 100y^2

Answer 47

12y=24+10y+24+10y+48+20y-48

see the mistakes you made here? This is missing all that stuff from above.

Answer 48

Yes, now do this again\[\Large 12y=(24+10y)^2+2(24+10y)-48 \]

Answer 49

12y= 576+480y+100y^2 +20y
12y= 100y^2 + 500y + 576

Answer 50

Yes, now solve for y using the quadratic formula .

Answer 51

uh.... no calc here... and i forgot that long go haha

Answer 52

You're on a computer, so you have a calculator. Use google if necessary. Google the quadratic formula.

Answer 53

\[\frac{ -500 \pm \sqrt{19,600} }{ 1,152 }\]

Answer 54

12y = 100y^2 + 500y + 576

Before using the quadratic formula, you have to get it equal to zero. You haven't used the quadratic formula correctly. It also shouldn't be something you forgot... memorize it.

http://www.purplemath.com/modules/quadform.htm it's right near the top.

Answer 55

its not working...

Answer 56

For ax2 + bx + c = 0, the value of x is given by: http://www.purplemath.com/modules/quads/qform01.gif

Answer 57

i know thats the formula

Answer 58

Then... why'd you say you forgot it?

Answer 59

can you use matrices and other rules?

Answer 60

if not , you can ask for miracles and best hope to an answer

Answer 61

@nincompoop The current question is not the one at the top.

Answer 62

ermmmm laughing out loud nvm then

Answer 63

i did forget it but i just looked it up and i already know..as in you didn tneed to put that last link.

Answer 64

i got the vid to work!!!

Answer 65

is that you in the vid?

Answer 66

Er what vid?

Answer 67

SQUIRREL. ♥

Answer 68

ok so now i got \[\frac{ 488 \pm \sqrt{7,744} }{ 200 }\]

Answer 69

@Sally♡ huh?

Answer 70

squiirrrreeeeeellllll ♥

Answer 71

Finish simplifying it.

Answer 72

Whispers "squirrels are furry."

Answer 73

Sally what are you talking about

Answer 74

Sorry lol. I like squirrels (;

Answer 75

Also it's NEGATIVE b in the formula, you just have b.

Answer 76

oh right..haha

Answer 77

soo -400/200 or -576/200

Answer 78

-2 or -2.88

Answer 79

Yes.

Answer 80

and thats y

Answer 81

wait but which one is it?

Answer 82

\[\Large x−10y=24\]\[\Large 12y=x^2+2x−48\]
Now find x using the first equation. Use BOTH y's to get 2 diff x's

Answer 83

i got 4 and 18.24

Answer 84

4 is right, 18.24 is not

Answer 85

oops - 4.8

Answer 86

Yep.

Answer 87

O_O why not use matrices?

Answer 88

ok so those two y's and x's are my answer?

Answer 89

I don't think you're done yet... you need to find x y z and u

Answer 90

this is an augmented matrix of 4 x 4

Answer 91

its a different question half way through this chat i asked another question :)

Answer 92

oh *facepalm

Answer 93

we just wolfram alpha for the top question...if you have another way oh doing the first one thoo id love to know it

Answer 94

hello?? @UsukiDoll

Answer 95

4 x 4 matrix style