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10 votes
Question 17 of 25

You need to solve a system of equations. You decide to use the elimination
method. Which of these is not allowed?
3x-2y=7
3x+4y=17
Equation 1
Equation 2
OA. Subtract equation 2 from equation 1.
OB. Subtract the left side of equation 2 from the left side of equation
1.
OC. Multiply equation 1 by 2. Then add the new equation to equation 2.

User Mike Shauneu
by
2.6k points

1 Answer

18 votes
18 votes

Answer:

The only methods allowed are

- "Subtract equation 2 from equation 1," and "Multiply equation 1 by 2. Then add the new equation to equation 2"

-

Explanation:

Subtract Eq 2 from Eq 1:

3x-2y=7

-3x-4y=-17

-6y = -10

y = (5/3)

Use y =(5/3) to solve for x in both equations.

x=(31/9)

Subtract the left side of equation 2 from the left side of equation No, this is not a legal operation.

Multiply equation 1 by 2. Then add the new equation to equation 2 Yes, this works. Instead of solving for y first, this method solves for x, which can then be used to find y:

2(3x-2y=7)

6x-4y=14

3x+4y=17

9x = 31 (y is eliminated)

x = (31/9)

Now use this to find y in either equation:

3x-2y=7

3x-2(31/9)=7

y = (5/3)

User Colton Myers
by
3.4k points
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