Question

Choose the correct option that explains what steps were followed to obtain the system of equations below

Answer 1

Answer:

option C is the correct answer

Step-by-step explanation:

System A:                                                  System B:

-x - 2y = 7    ........(1)                               -x - 2y = 7    .......(3)  

5x - 6y = -3  ........(2)                                  -16y= 32  ........(4)

Solution for system A: ( -3, -2)

For option A

Multiply the first equation by 3

3(- x - 2y) = 3(7)         ⇒     - 3x - 6y = 21 ........... (5)

Add equation 2 and 5

  5x - 6y = -3

- 3x - 6y = 21

  2x -12y = 18   ⇒  2( x - 6y ) = 2( 9 )    ⇒   x - 6y = 9

Option A is not equal to equation in system B so now we check option B.

 For option B

Multiply the first equation by -5

-5(- x - 2y) = -5(7)         ⇒    5x + 10y = -35 ........... (6)

Add equation 2 and 6

  5x - 6y = -3

  5x + 10y = -35

  10x + 4y = -38   ⇒   2( 5x + 2y ) = 2(-19)    ⇒  5x + 2y = -19

Option B is not equal to equation in system B so now we check option C.

For option C

Multiply the first equation by 5            

5(- x - 2y) = 5(7)         ⇒   - 5x - 10y = 35 ........... (7)

Add equation 2 and 7

  5x - 6y = -3

- 5x - 10y = 35

    0 - 16y = 32   ⇒   -16y = 32

Option C is equal to equation in system b so now we check if the solution to system B is same as system A.  

Solution to system B:

First, we find value of y from equation 4:

-16y = 32   ⇒    y = $\frac{32}{-16}$   ⇒    y = -2

Now, we put value of y in equation 3 to find value of x:

-x - 2y = 7  ⇒  -x - 2(-2) = 7   ⇒  -x + 4 = 7   ⇒  -x = 7 - 4  ⇒  -x = 3

multiply both sides by -1

-1 × (-x) = -1 × (3)       ⇒     x = -3

Solution of system B = (-3, -2)

Solution of system B is the same as system A, so option C is correct.

Answer 2

Answer: To get system B, the second equation in system A was replaced by the sum of that equation and the first equation multiplied by 5. The solution to system B will be the same as the solution to system A.

Step-by-step explanation:

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