Question

Solve the system of equations using elimination.

4x - 7y = 5
8x + 3z = -35
6y + 3z = 15

Answer 1

x = -11.88 y = -7.5 z =20

Explanation:

8x -6y = -50

-2( 4x -7y = 5 )

8x -6y = -50

-8x +14y = -10

8y= -60

y= -7.5

4x -7(-7.5) = 5

4x + 52.5 = 5

4x = -47.5

x= -11.88

6(-7.5) +3z = 15

-45 +3z = 15

45 45

3z = 60

z= 20

Answer 2

x=-5/8, y=15/2, z=-10. (-5/8, 15/2, -10).

Explanation:

4x-7y=5

8x+3z=-35

6y+3z=15

----------------

4x=7y+5

2(4x)=2(7y+5)

8x=14y+10

14y+10+3z=-35

14y+3z=-35-10

14y+3z=-45

-----------------------

14y+3z=-45

6y+3z=15

------------------

14y+3z=-45

-(6y+3z)=-15

---------------------

14y+3z=-45

-6y-3z=-15

--------------------

8y=-60

simplify,

y=15/2

6(15/2)+3z=15

45+3z=15

3z=15-45

3z=-30

z=-30/3

z=-10

8x+3(-10)=-35

8x-30=-35

8x=-35+30

8x=-5

x=-5/8

x=-5/8, y=15/2, z=-10.