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Select all correct answers. 12. The solution to the system of equations x y = 1 and x - y = - 7 is (- 3, 4) This solution is NOT a solution to which of the following equations? x y - 2(x - y) = 1 - 2(- 7) B 3(x y) x - y = 3(1) - 7 C x y 5(x - y) = 5(1) - 7 D - 4(x y) x - y = 1 - 4(- 7) E x y - x y = 1 7

Relax

Respuesta :

Answer:(-3, 4).

Step-by-step explanation:

Let's check each option to see if the given solution, (-3, 4), satisfies the equation:

A.

οΏ½

οΏ½

βˆ’

2

(

οΏ½

βˆ’

οΏ½

)

=

1

βˆ’

2

(

βˆ’

7

)

xyβˆ’2(xβˆ’y)=1βˆ’2(βˆ’7)

(

βˆ’

3

)

(

4

)

βˆ’

2

(

(

βˆ’

3

)

βˆ’

4

)

=

1

βˆ’

2

(

βˆ’

7

)

(βˆ’3)(4)βˆ’2((βˆ’3)βˆ’4)=1βˆ’2(βˆ’7)

(

βˆ’

12

)

βˆ’

2

(

βˆ’

7

)

=

1

βˆ’

14

(βˆ’12)βˆ’2(βˆ’7)=1βˆ’14

βˆ’

12

+

14

=

1

βˆ’

14

βˆ’12+14=1βˆ’14

2

=

βˆ’

13

2=βˆ’13 (False)

B.

3

(

οΏ½

οΏ½

)

=

οΏ½

βˆ’

οΏ½

3(xy)=xβˆ’y

3

(

(

βˆ’

3

)

(

4

)

)

=

(

βˆ’

3

)

βˆ’

4

3((βˆ’3)(4))=(βˆ’3)βˆ’4

3

(

βˆ’

12

)

=

βˆ’

3

βˆ’

4

3(βˆ’12)=βˆ’3βˆ’4

βˆ’

36

=

βˆ’

7

βˆ’36=βˆ’7 (False)

C.

οΏ½

οΏ½

βˆ’

5

(

οΏ½

βˆ’

οΏ½

)

=

5

(

1

)

βˆ’

7

xyβˆ’5(xβˆ’y)=5(1)βˆ’7

(

βˆ’

3

)

(

4

)

βˆ’

5

(

(

βˆ’

3

)

βˆ’

4

)

=

5

βˆ’

7

(βˆ’3)(4)βˆ’5((βˆ’3)βˆ’4)=5βˆ’7

βˆ’

12

βˆ’

5

(

βˆ’

7

)

=

βˆ’

2

βˆ’12βˆ’5(βˆ’7)=βˆ’2

βˆ’

12

+

35

=

βˆ’

2

βˆ’12+35=βˆ’2

23

=

βˆ’

2

23=βˆ’2 (False)

D.

βˆ’

4

(

οΏ½

οΏ½

)

=

οΏ½

βˆ’

οΏ½

βˆ’4(xy)=xβˆ’y

βˆ’

4

(

(

βˆ’

3

)

(

4

)

)

=

(

βˆ’

3

)

βˆ’

4

βˆ’4((βˆ’3)(4))=(βˆ’3)βˆ’4

βˆ’

4

(

βˆ’

12

)

=

βˆ’

3

βˆ’

4

βˆ’4(βˆ’12)=βˆ’3βˆ’4

48

=

βˆ’

7

48=βˆ’7 (False)

E.

οΏ½

οΏ½

βˆ’

οΏ½

οΏ½

=

1

βˆ’

7

xyβˆ’xy=1βˆ’7

(

βˆ’

3

)

(

4

)

βˆ’

(

βˆ’

3

)

(

4

)

=

1

βˆ’

7

(βˆ’3)(4)βˆ’(βˆ’3)(4)=1βˆ’7

βˆ’

12

+

12

=

βˆ’

6

βˆ’12+12=βˆ’6

0

=

βˆ’

6

0=βˆ’6 (False)