SOLUTION: i don't have any idea in solving this elimination method. Can you help me? Please 3x+5y-2z=7 5x+4y+5z=-13 3x-2y+4z=-3 Please help me.

Algebra ->  College  -> Linear Algebra -> SOLUTION: i don't have any idea in solving this elimination method. Can you help me? Please 3x+5y-2z=7 5x+4y+5z=-13 3x-2y+4z=-3 Please help me.      Log On


   

Question 849834: i don't have any idea in solving this elimination method. Can you help me? Please
3x+5y-2z=7
5x+4y+5z=-13
3x-2y+4z=-3
Please help me.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.3x%2B5y-2z=7
2.5x%2B4y%2B5z=-13
3.3x-2y%2B4z=-3
Subtract eq. 3 from eq. 1,
3x%2B5y-2z-3x%2B2y-4z=7%2B3
4.7y-6z=10
Multiply eq. 1 by 5 and eq. 2 by -3 and add them,
15x%2B25y-10z-15x-12y-15z=35%2B39
5.13y-25z=74
Now x is elmininated.
Multiply eq. 4 by 13 and eq. 5 by (-7) and add them,
91y-78z-91y%2B175z=130-518
97z=-388
z=-4
Now back substitute to find y
7y-6%28-4%29=10
7y=-14
y=-2
and finally,
3x%2B5%28-2%29-2%28-4%29=7
3x-10%2B8=7
3x=9
x=3