## Calcmathlete 3 years ago 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?

1. Calcmathlete

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...

2. NotTim

its also...vector like...

3. NotTim

Almost...

4. NotTim

I meant

5. Calcmathlete

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

6. swissgirl

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

7. swissgirl

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

8. Calcmathlete

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

9. Hero

I think that also fails the x < y < z

10. Hero

since in your case y > z

11. swissgirl

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

12. Hero

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

13. KingGeorge

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

14. Calcmathlete

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

15. Calcmathlete

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