Question

solve each system of equations. x+y-z=-1 x+y+z=3 3x-2y-z=-4

Answer 1

any one please for the love of god explain how to do these!

Answer 2

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

Answer 3

@amistre64

Answer 4

@Hero @jim_thompson5910

Answer 5

@Psymon

Answer 6

im not asking for the answers straight out. i just want to know how to do these?

Answer 7

@dmezzullo

Answer 8

@satellite73

Answer 9

@DDCamp

Answer 10

See how the first 2 equations look really similar, and have the same x and y coefficients (1)?
Subtract equation 2 from equation 1 to get:
-2z = -4 → z = 2

Answer 11

yes but the z's are a negative and a positive so then what?

Answer 12

What happens when you subtract z from - z?

Answer 13

no more z

Answer 14

so would that make z 0?

Answer 15

x + y - z = -1
x + y + z = 3
-------------add
2x + 2y = 2

x + y + z = 3
3x - 2y - z = -4
--------------add
4x - y = -1

2x + 2y = 2 -->(-2)
4x - y = -1
----------------
-4x - 4y = -4 (result of multiplying by -2)
4x - y = -1
---------------add
-5y = -5
y = 1

4x - y = -1
4x - 1 = -1
4x = -1 + 1
4x = 0
x = 0

x + y + z = 3
0 + 1 + z = 3
1 +z = 3
z = 3 - 1
z = 2

check...
x + y - z = -1
0 + 1 - 2 = -1
-1 = -1 (correct)

Any questions, feel free to ask

Answer 16

Thank you so much!

Answer 17

no problem :)