For which value of "k" does the system below not have a unique equation?
System:
-1x+7y+2z=6
2x+1y+kz=-11
3x-6y-2z=-1

Answers:
a. x
b. y
c. z
d. It represents none of the variables.

Question

For which value of "k" does the system below not have a unique equation? 
System:
-1x+7y+2z=6
2x+1y+kz=-11
3x-6y-2z=-1

Answers:
a. x
b. y
c. z
d. It represents none of the variables.

anonymous · Answer

determinant is b^2 - 4ac

anonymous · Answer

is determinant is larger than 0 than it does NOT

anonymous · Answer

have a unique soltion

anonymous · Answer

so that means?

anonymous · Answer

you want me to do your homework problems??

anonymous · Answer

what do i get in return?

anonymous · Answer

No I just need help understanding how to do these! This is just a practice sheet not really homework, but my teacher didn't explain this well at all!

anonymous · Answer

hmm is this matrrix algebra?

anonymous · Answer

yes

anonymous · Answer

university work? or highschool

anonymous · Answer

high school.

anonymous · Answer

damm u must go to ahard highschool cause that question is a university level

anonymous · Answer

it's just algebra 2 for juniors!

anonymous · Answer

lol seems pretty hard

anonymous · Answer

lol is the asnwer D??

anonymous · Answer

okay so what does that mean anyway? like is it no solution (d)? ah :(

anonymous · Answer

not sure hnow to do it actaully

anonymous · Answer

oh crap i meant the answer choices are:
a)-8
b) -2
c) 0
d) 5 

:P

hero · Answer

It's not that hard. Just plug and play

anonymous · Answer

yeah okay i'm just really confused!

anonymous · Answer

hero would u put the qeqatuons into a matrix??

hero · Answer

No

anonymous · Answer

but it will take you 2 years to find it out

hero · Answer

No it wouldn't

anonymous · Answer

trying to solve for all those variables

hero · Answer

It's not as hard as you think

anonymous · Answer

looks like a mission question to me lol

hero · Answer

The way I do it, I wouldn't be that difficult

anonymous · Answer

how would u do it bro?

hero · Answer

I won't say how I do it because you would say it IS difficult

anonymous · Answer

okay i got an answer but can someone tell me what they got so i know i did it right? I got 0.

anonymous · Answer

just say please i wanna learn teach me ur math awesomeness

hero · Answer

Well, the first thing I'd try is wolfram alpha

anonymous · Answer

shahahahahahahahahahahah
looooooooooooooooooooooooooooooooooooo

anonymous · Answer

loooooooooooooooooooooooooooooooooooooooooooool lmfaoooooooo ahahahhhaha

anonymous · Answer

hello? HELP!

hero · Answer

Okay, hold on

anonymous · Answer

lol wolfram alpha is the best i alwasy use it

anonymous · Answer

hey girl use wolfram alpha

anonymous · Answer

its the sexiest program in exsistenace today

anonymous · Answer

dont worry Hero is gonna put it into wolfram alpha for you you can use a computer in ur exam

hero · Answer

Actually, I don't know the input to systems of equations for wolfram alpha, but I have another resource. It'll take a bit though

anonymous · Answer

okay

anonymous · Answer

lol hero i doubt she has a computer for her exams

anonymous · Answer

well i just want him to check my answer because i dont know if i did it right!

anonymous · Answer

u said 0 which is not even mak3es sense inb the context of the question

anonymous · Answer

oh...

anonymous · Answer

actuqly it does i misread the question

anonymous · Answer

okay good

anonymous · Answer

anyway do u even understand what the question is asking u?

anonymous · Answer

is math ur avourite subjedt?

hero · Answer

Yeah, this is tougher than I thought

hero · Answer

I can figure it out, but it would take time....just guess

anonymous · Answer

hero

anonymous · Answer

its a mission question lol

anonymous · Answer

goodluck wasting 5 houirs of ur time for some random chick

hero · Answer

actually, just noticed something...you can combine the first and 3rd equations

hero · Answer

That would make it easier

anonymous · Answer

ok but it will still tkae pretty long

hero · Answer

Not really, k = 0 is the correct answer

anonymous · Answer

fuuuuk that was fast

hero · Answer

If you combine the first and third equations, z cancels

anonymous · Answer

k hero now u have to answer all 
my math question whe i have some

hero · Answer

Okay, but I'm sure you're going to pay me afterwards right?

anonymous · Answer

haahah lol im sure we can arrange something of that sort

hero · Answer

Okay then, bring 'em on

anonymous · Answer

lol i actaully studying an electrical engineerring subject atm so i have noi math questions to give u

hero · Answer

Oh well...Yeah, don't even try to give me circuit questions....I did those before, but forgot...the only thing I remember is V = IR

anonymous · Answer

haha ok this stuff is making me so depressed

hero · Answer

What happened to amada?

anonymous · Answer

i think she fainted from all the heat

hero · Answer

I'm sorry to hear that

anonymous · Answer

she didnt even thanks you :(

hero · Answer

At least she got the answer.

hero · Answer

I think she got it....I did post it

anonymous · Answer

yeh she said 0 but it was a pure guess ol

hero · Answer

It was a good guess

anonymous · Answer

lol true

anonymous · Answer

the above system wont have a unique solution if one of the rows is a combination of the other 2.
Notice that for the x's  and y's, if you add the 3rd and 1st row, you will get the second row.
That should let you know that if you add the 1st and 3rd row for z, that will produce your answer.
2+ (-2) = 0

hero · Answer

yeah, joe I already figured that out and posted it :P

anonymous · Answer

Another way to do this problem (although a bit more tedious), is to do row operations.