Galena is solving the following system. 3x+2y+3z =5 7x+y +7z=-1 4x-4y-z=-3
step 1 she multiplies equation (3) by 3 and adds it to equation (1)
step 2 she multiplies equation (3) by -7 and adds it to equation (2)
which statement explains galena’s mistake?
1 she adds equation 1 instead of equation 2 in step 1
2 she does not multiply equation 3 in step 1 by the correct value
3 she did not multiply equation 3 in step 2 by the correct value
4 she added equation 2 instead of equation 1 in step 2

She did not multiply equation 3 in step 2 by the correct value.

Step-by-step explanation:

Given:

In order to solve this, we need to eliminate any one variable and then form a simultaneous equation with the remaining two variables. Then, we nee to solve the simultaneous equation.

Here, Galena is trying to eliminate the variable first.

Step 1:  She multiplies equation (3) by 3 and adds it to equation (1)

Let us multiply equation (3) by 3

Now, adding this to equation 1 will cancel out z terms.

Now, she need to make one more equation in .

Step 2: She multiplies equation (3) by -7 and adds it to equation (2)

Multiplying equation (3) by -7 will give,

Now, adding this to equation 2 will not cancel out z terms.

So, she makes mistake in step 2 as the terms are not being cancelled.

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step-by-step explanation: