Let the solution (x, y, z) satisfy the following equations: x + y + z = -1, xy + xz + yx = -17, xyz = -15. If x

Question

Let the solution (x, y, z) satisfy the following equations: x + y + z = -1, xy + xz + yx = -17, xyz = -15.  If x < y < z, what is the value of: x - 2y + 4z?

anonymous · Answer

And this is supposed to be a speed math question as in you should be able to do this in like 30 seconds...not sure how to do it though...

nottim · Answer

its also...vector like...

nottim · Answer

Almost...

nottim · Answer

I meant

anonymous · Answer

Seriously? That's like 5 questions that pertain to vectors when I have not learned them... :/

swissgirl · Answer

well for starter the biggest lead is xyz=-15
that shows me that there has to be a 1,3 and 5 involved

swissgirl · Answer

next x+y+z=-1
-5+3+1=-1

anonymous · Answer

But when you plug it into xy + xz + yx, it doesn't work...

hero · Answer

I think that also fails the x < y < z

hero · Answer

since in your case y > z

swissgirl · Answer

well no u wld just switch around the variables that is no big deal

hero · Answer

Maybe let x = -5, y = 1, z = 3

kinggeorge · Answer

Did you mistype the problem? Or is it correct as written?

Should it be "xy + xz + yz = -17" instead of "xy + xz + yx = -17?"

anonymous · Answer

That's what it says on the document...thinking it's a typo though...

anonymous · Answer

Alright. I think it is just a typo. Thanks swiss!