Question

If you were to use the elimination method to solve the following system, choose the new system of equations that would result after the variable z is eliminated in the second and third equations, then the first and second equations.

5x + 2y + z = -2
3x + 4y + 3z = 2
-4x - 3y - 3z = 1

Answer 1

@phi

Answer 2

cancel out z in 2nd and 3rd equation

Answer 3

after the variable z is eliminated in the second and third equations,

that means look at only the 2nd and 3rd equations:
3x + 4y + 3z = 2
-4x - 3y - 3z = 1

eliminate the z means make the numbers in front of z be "equal and opposite"
i.e. one the negative of the other. once you get that, add the two equations, and the z term will become zero.

In this case, we already have 3 and -3, so just add.
what do you get ?

Answer 4

0

Answer 5

add the two equations. do you know how to do that ?

Answer 6

kind of i will try

Answer 7

-x+7y=3

Answer 8

phi you here

Answer 9

4y-3y is not 7y

Answer 10

y

Answer 11

-x+y=3

Answer 12

Is that enough to eliminate some of the choices?

Answer 13

yes thank you, i have just one more

Answer 14

then the first and second equations.
5x + 2y + z = -2
3x + 4y + 3z = 2

In case you had to do this:
multiply the first eq by -3 (that will make the # in front of z be -3 which is the opposite of +3 in the 2nd equation:

-15x -6y -3z= +6
3x + 4y + 3z = 2

add the 2 equations, just like before.