Question

2x – 3y - 9z = 113x + 3z= – 5-3x + y - 4z = 8 solve for x,y,z​

Answer 1

Answer:

x = 0, y = 1.333, z = -1.667 ( to the nearest thousandth).

Step-by-step explanation:

2x – 3y - 9z = 11      A

3x + 3z= – 5            B

-3x + y - 4z = 8        C

Multiply Equation  C by 3:

-9x + 3y - 12z = 24     D  

Adding A + D:

-7x - 21z =  35             Divide by 7:

-x -  3z = 5             E

Adding B + E:

2x = 0

x = 0

Plugging in x = 0 into equation B:

3(0) + 3z = -5

z = -5/3

z = -1 .667

Now plugging the values of y and z into equation A:

2(0) - 3y - 9(-5/3) = 11

-3y = 0 + 11 + 9(-5/3) = -4

y = 4/3 = 1.333.

Answer 2

Answer:

Step-by-step explanation:

2x – 3y - 9z = 11   ... (1)

3x + 3z= – 5  ....(2)

-3x + y - 4z = 8  ....(3)

add (3) and (2) : y - z = 3   so : y = z+3    (*)

put this value in (1) : 2x-3(z+3) -9z = 11

2x-3z -9-9z = 11    so : 2x =12z+20

x = 6z+10   ....(**)

put this value in (2) : 3(6z+10)+3z = -5

18z+30+3z=-5

21z = -35  

z = -35/21= - 5/3

put this value in (*) and (**) you have x and y .