Question

A student is trying to solve the system of two equations given below:

Equation P: y + z = 6
Equation Q: 3y + 4z = 1

Which of these is a possible step used in eliminating the y-term?

(y + z = 6) ⋅ 4
(3y + 4z = 1) ⋅ 4
(y + z = 6) ⋅ −3
(3y + 4z = 1) ⋅ 3

Answer 1

do you know how to use the elimination theory?

Answer 2

@IconForHire56 Do you?

Answer 3

not one bit but need a 60 to pass my pre test or i fail the test and won't be able to finish the class

Answer 4

When you use the elimination method, you need to add the two equations to eliminate one variable.
For example, if you had the system, of equations:
x + y = 8
x - y = 4
you can see that if you add the equations, the y and the -y will add to zero, eliminating the y variable. Then you have a single equation just in x, and you can solve for x.

Answer 5

In your case, if you just add the equations, y + 3y = 4y, and the y is not eliminated.
z + 4z = 5z, and the z is not eliminated, so just adding the equations does not work.

Answer 6

In your case, to use the elimination method, you need one extra step.
That step is to multiply one of the equations by a number, so that then when you add the equations a variable will be eliminated.

Answer 7

Look at choice A.
You multiply the entire first equation by 4.
The first equation ends up becoming:
4y + 4z = 24
When you add this equation to the second equation
3y + 4z = 1,
4y + 3y = 7y, and the y is not eliminated, and
4z + 4z = 8z, and the z is not eliminated.
That means choice A does not help eliminate a variable, and is not the answer.

Answer 8

Now do the same for the other three choices to see which one will help eliminate a variable.