Saturday

April 19, 2014

April 19, 2014

Posted by **ZUkii** on Monday, November 21, 2011 at 2:39am.

x- 2y+ 3z = 5

3x + y = -5

-2x+y + z = 8

- Math (linear algebra) -
**Dr Russ**, Monday, November 21, 2011 at 4:12amx- 2y+ 3z = 5

3x + y = -5

-2x+y + z = 8

First thing to check is that we have three equations and three unknowns, which is fine. If there are more unknowns than equations then there is a problem with the question.

x- 2y+ 3z = 5

3x + y = -5

-2x+y + z = 8

we need to eliminate one unknown by combining pairs of equations. Lets say we remove the y terms.

x- 2y+ 3z = 5

3x + y = -5 (multiply by 2)

x- 2y+ 3z = 5

6x + 2y = -10

Add these two and y terms are removed.

7x+3z=-5

Do the same with, but this time subtract the two and the y terms are removed

3x + y = -5

-2x+y + z = 8

5x-z=-13

We now have two equations and two unknwons

7x+3z=-5

5x-z=-13 (multiply by 3)

7x+3z=-5

15x-3z=-39

and add

22x=-44, so x=-2

substitute in here to find y

3x + y = -5

the substitute in one of the above to find z

**Related Questions**

linear algebra - Use an inverse matrix to solve each system of linear equations...

linear algebra - Use an inverse matrix to solve each system of linear equations...

linear algebra - Use an inverse matrix to solve each system of linear equations...

maths - use the substitution method to solve the linear system. 1. 3x=9 -x+2y=9 ...

math/algebra - how do I solve system of linear inequalities by graphing x-y<=...

Discrete Math - I am really stuck on these problems. I've worked a lot of them ...

algebra - the primeter of a rectangle is 24ft. the length is 2 ft longer than ...

MaTh = Algebra = help - Solve this system of linear equaiton by an algebraic ...

Algebra - To solve the system of equations, which expression could be ...

algebra - theperimeter of a rectangle is32 ft. The lenght is 12 ft longer than ...