Expert: Sherman D. - 7/29/2009

Question
Solve the system of equations using matrices.

2x+y+z = 5
4x-y-3z= 1
8x+y-z = 5

My main problem is using the right numbers to multiply and add to the rows...i tried it on many problems..but i am somehow got stucked on every single on them..is there a trick :P to solve this kind of problems ? Please help..i have a test tomorrow !

Answer
2x + y + z = 5
4x - y - 3z = 1
8x + y - z = 5

2x + y + z = 5
8x + y - z = 5

2x + y = 5
y = -2x + 5

8x + y = 5
y = -8x + 5

-2x + 5 = -8x + 5
-2x = -8x
x = 0

2x + z = 5
4x - 3z = 1

6x + 3z = 15
4x - 3z = 1

10x = 16
x = 8/5

8(8/5) - z = 5
64 - 5z = 25
-5z = -39
z = 39/5

x = 8/5
y = 0
z = 39/5

however if you plug those in it won't work.

so i went to quickmath.com, click on Solve which is located under Equations, then clicked on Advanced, then copied an pasted the problem in, added z on the right side, clicked Solved, and it says that there is no solution.

ANS : No Solution