Can someone help me with my homeowrk in Algerba II.

We'll help you but we won't do it for you. Do you have any specific questions you need help with? Post them here.

I am willing to do the work.
It's a three variable problem
7x-3y+4z=-14
8x+2y-24z=18
6x-10y+8z=-24

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Originally Posted by sweetpea82093

I am willing to do the work.
Its a three variable problem
7x-3y+4z=-14
8x+2y-24z=18
6x-10y+8z=-24

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For starters, I'd recommend you combine your 1st and 3rd equations and eliminate the z. This will leave you with an equation containing x and y. Then combine your 1st. And 2nd. Equations and again eliminate the z. This will leave you with another equation containing x and y. Then combine those and eliminate the x or y ; your choice. Finally, solve for the remaining variable. Then back-substitute that into one of your 2-variable equations to solve for the 2nd variable. Finally, back-substitute those into one of your original 3-variable equations to solve for the 3rd. And remaining variable.

Finally, solve for the remaining variable. Then back-substitute that into one of your 2-variable equations to solve for the 2nd variable. Finally, back-substitute those into one of your original 3-variable equations to solve for the 3rd. And remaining variable.

I don't know how to do from there on.

Quote:

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Originally Posted by sweetpea82093

Finally, solve for the remaining variable. Then back-substitute that into one of your 2-variable equations to solve for the 2nd variable. Finally, back-substitute those into one of your original 3-variable equations to solve for the 3rd. and remaining variable.

i don't know how to do from there on.

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But that's the last step ; there is no "from there on."

Okay so I solved it but got the wrong answers

Quote:

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Originally Posted by sweetpea82093

okay so i solved it but got the wrong answers

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How do you know you got the wrong answers? Show me what you did and I can steer you in the right direction.

my text book shows me the right answer and that's not what I got, this is what did.

7x-3y+4z=-14
6x-10y+8z=-24
-14x+6y-8z=-38
-8-4y=-62

7x-3y+4z=-14
8x+2y-24z=18
42x-18y+24z=-84
50x-16y=-46

I then combined my two answers and got
32+16y=248
y=13.5

x=3.4
z=2.7/4

Na, something is wrongs with your logic:

7x-3y+4z=-14
6x-10y+8z=-24

Multiply the 1st equation by -2

14x+6y-8z=28
6x-10y+8z=-24

Now add.

Try not to subtract. Always multiply by a negative number and ADD.

Mistake #1; What's 2(-14)? It's not -38. I'm also lost when you say "I then combined my two answers and got
32+16y=248".

how did you get this?


14x+6y-8z=28
6x-10y+8z=-24

s_cianci

I combined 50x-16y=-46 and -8x-4y=14
and got y is equal to -5.5
after I changed the mistake you told me about and its still not right

Quote:

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Originally Posted by sweetpea82093

how did you get this?


14x+6y-8z=28 = (7x-3y+4z=-14)*-2; oops sign problems
6x-10y+8z=-24

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New eqn:
-14x+6y-8z=28
6x-10y+8z=-24

6x-10y+8z=-24
so where did you get that

Quote:

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I am willing to do the work.
It's a three variable problem
7x-3y+4z=-14 (The unmodified eqn)
8x+2y-24z=18 (Use later)
6x-10y+8z=-24 (what you asked about)

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..

Take a look here: System of linear equations - Wikipedia, the free encyclopedia

The easiest way to solve is to use Cramer's rule, but your not there yet.

Thank you.