Question 464634
solve this system of equation 
2x+y-z=10
6x+5y-2z=23
3x-y+z=5
...
1) 2x+y-z=10
2) 6x+5y-2z=23
3) 3x-y+z=5
..
3) 3x-y+z=5
1) 2x+y-z=10
add, eliminating y & z
4) 5x=15
x=3
..
2) 6x+5y-2z=23
5) 4x+2y-2z=20 (multiply eq 1 by 2)
subtract
2x+3y=3
sub x
2*3+3y=3
6+3y=3
3y=3-6=-3
y=-1
..
3) 3x-y+z=5
sub x & y
3*3-(-1)+z=5
9+1+z=5
z=5-10=-5
..
Check:
1) 2x+y-z=6-1+5=10
2) 6x+5y-2z=18-5+10=23
3) 3x-y+z=5=9+1-5=5
Ans:
x=3
y=-1
z=-5