Scroll:Algebra new >> Elimination method >> ps (4540)


Written Instructions:

For each Multiple Choice Question (MCQ), four options are given. One of them is the correct answer. Make your choice (1,2,3 or 4). Write your answers in the brackets provided..

For each Short Answer Question(SAQ) and Long Answer Question(LAQ), write your answers in the blanks provided.

Leave your answers in the simplest form or correct to two decimal places.



 

1)  

 10x -  5y = xy,       7x - 3y = 7xy

x =

y =


Answer:_______________




2)  

 11x -  7y = xy,       9x - 4y = 6xy

x =

y =


Answer:_______________




3)  

 11x -  7y = xy,       8x - 4y = 7xy

x =

y =


Answer:_______________




4)  

 11x -  7y = xy,       9x - 4y = 6xy

x =

y =


Answer:_______________




5)  

 9x -  7y = xy,       8x - 4y = 6xy

x =

y =


Answer:_______________




6)  

 11x -  7y = xy,       9x - 4y = 6xy

x =

y =


Answer:_______________




7)  

 10x -  5y = xy,       9x - 3y = 7xy

x =

y =


Answer:_______________




8)  

 11x -  7y = xy,       9x - 4y = 6xy

x =

y =


Answer:_______________




9)  

 10x -  6y = xy,       8x - 4y = 7xy

x =

y =


Answer:_______________




10)  

 11x -  7y = xy,       9x - 4y = 6xy

x =

y =


Answer:_______________




 

1)  

 10x -  5y = xy,       7x - 3y = 7xy

x = Answer: 112.60

y = Answer: 16.40


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 10x - 5y = xy.

Dividing by xy,

10y -   5x = 1

- 5x + 10y = 1 ...... (1)

Consider, 7x - 3y = 7xy

Dividing by xy.

- 3x + 7y = 7  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-5a + 10b = 1   ......    (3)

-3a + 7b = 7  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 3         -15a + 30b = 3

(4) x 5         -15a + 35b = 35

                                -5b = -32

                                  b = 325

                                  b = 6.40.

Substituting b = 6.40 in (3).

-5a + 10(6.40) = 1.

-5a + 64 = 1

-5a = 1 - 64

-5a = -63

          a = 635

          a = 12.60

Hence a = 12.60  ⇒     x = 112.60

           b = 6.40   ⇒     y = 16.40 .

The system has two solutions (0,0) and ( 112.60 , 16.40 ).

 

 



2)  

 11x -  7y = xy,       9x - 4y = 6xy

x = Answer: 13

y = Answer: 12


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 9x - 4y = 6xy

Dividing by xy.

- 4x + 9y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 9b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 63b = 42

                                -19b = -38

                                  b = 3819

                                  b = 2.

Substituting b = 2 in (3).

-7a + 11(2) = 1.

-7a + 22 = 1

-7a = 1 - 22

-7a = -21

          a = 217

          a = 3

Hence a = 3  ⇒     x = 13

           b = 2   ⇒     y = 12 .

The system has two solutions (0,0) and ( 13 , 12 ).

 

 



3)  

 11x -  7y = xy,       8x - 4y = 7xy

x = Answer: 15.75

y = Answer: 13.75


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 8x - 4y = 7xy

Dividing by xy.

- 4x + 8y = 7  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 8b = 7  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 56b = 49

                                -12b = -45

                                  b = 4512

                                  b = 3.75.

Substituting b = 3.75 in (3).

-7a + 11(3.75) = 1.

-7a + 41.25 = 1

-7a = 1 - 41.25

-7a = -40.25

          a = 40.257

          a = 5.75

Hence a = 5.75  ⇒     x = 15.75

           b = 3.75   ⇒     y = 13.75 .

The system has two solutions (0,0) and ( 15.75 , 13.75 ).

 

 



4)  

 11x -  7y = xy,       9x - 4y = 6xy

x = Answer: 13

y = Answer: 12


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 9x - 4y = 6xy

Dividing by xy.

- 4x + 9y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 9b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 63b = 42

                                -19b = -38

                                  b = 3819

                                  b = 2.

Substituting b = 2 in (3).

-7a + 11(2) = 1.

-7a + 22 = 1

-7a = 1 - 22

-7a = -21

          a = 217

          a = 3

Hence a = 3  ⇒     x = 13

           b = 2   ⇒     y = 12 .

The system has two solutions (0,0) and ( 13 , 12 ).

 

 



5)  

 9x -  7y = xy,       8x - 4y = 6xy

x = Answer: 12.30

y = Answer: 11.90


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 9x - 7y = xy.

Dividing by xy,

9y -   7x = 1

- 7x + 9y = 1 ...... (1)

Consider, 8x - 4y = 6xy

Dividing by xy.

- 4x + 8y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 9b = 1   ......    (3)

-4a + 8b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 36b = 4

(4) x 7         -28a + 56b = 42

                                -20b = -38

                                  b = 3820

                                  b = 1.90.

Substituting b = 1.90 in (3).

-7a + 9(1.90) = 1.

-7a + 17.1 = 1

-7a = 1 - 17.1

-7a = -16.1

          a = 16.17

          a = 2.30

Hence a = 2.30  ⇒     x = 12.30

           b = 1.90   ⇒     y = 11.90 .

The system has two solutions (0,0) and ( 12.30 , 11.90 ).

 

 



6)  

 11x -  7y = xy,       9x - 4y = 6xy

x = Answer: 13

y = Answer: 12


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 9x - 4y = 6xy

Dividing by xy.

- 4x + 9y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 9b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 63b = 42

                                -19b = -38

                                  b = 3819

                                  b = 2.

Substituting b = 2 in (3).

-7a + 11(2) = 1.

-7a + 22 = 1

-7a = 1 - 22

-7a = -21

          a = 217

          a = 3

Hence a = 3  ⇒     x = 13

           b = 2   ⇒     y = 12 .

The system has two solutions (0,0) and ( 13 , 12 ).

 

 



7)  

 10x -  5y = xy,       9x - 3y = 7xy

x = Answer: 14.06

y = Answer: 12.13


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 10x - 5y = xy.

Dividing by xy,

10y -   5x = 1

- 5x + 10y = 1 ...... (1)

Consider, 9x - 3y = 7xy

Dividing by xy.

- 3x + 9y = 7  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-5a + 10b = 1   ......    (3)

-3a + 9b = 7  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 3         -15a + 30b = 3

(4) x 5         -15a + 45b = 35

                                -15b = -32

                                  b = 3215

                                  b = 2.13.

Substituting b = 2.13 in (3).

-5a + 10(2.13) = 1.

-5a + 21.3 = 1

-5a = 1 - 21.3

-5a = -20.3

          a = 20.35

          a = 4.06

Hence a = 4.06  ⇒     x = 14.06

           b = 2.13   ⇒     y = 12.13 .

The system has two solutions (0,0) and ( 14.06 , 12.13 ).

 

 



8)  

 11x -  7y = xy,       9x - 4y = 6xy

x = Answer: 13

y = Answer: 12


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 9x - 4y = 6xy

Dividing by xy.

- 4x + 9y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 9b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 63b = 42

                                -19b = -38

                                  b = 3819

                                  b = 2.

Substituting b = 2 in (3).

-7a + 11(2) = 1.

-7a + 22 = 1

-7a = 1 - 22

-7a = -21

          a = 217

          a = 3

Hence a = 3  ⇒     x = 13

           b = 2   ⇒     y = 12 .

The system has two solutions (0,0) and ( 13 , 12 ).

 

 



9)  

 10x -  6y = xy,       8x - 4y = 7xy

x = Answer: 17.75

y = Answer: 14.75


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 10x - 6y = xy.

Dividing by xy,

10y -   6x = 1

- 6x + 10y = 1 ...... (1)

Consider, 8x - 4y = 7xy

Dividing by xy.

- 4x + 8y = 7  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-6a + 10b = 1   ......    (3)

-4a + 8b = 7  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -24a + 40b = 4

(4) x 6         -24a + 48b = 42

                                -8b = -38

                                  b = 388

                                  b = 4.75.

Substituting b = 4.75 in (3).

-6a + 10(4.75) = 1.

-6a + 47.5 = 1

-6a = 1 - 47.5

-6a = -46.5

          a = 46.56

          a = 7.75

Hence a = 7.75  ⇒     x = 17.75

           b = 4.75   ⇒     y = 14.75 .

The system has two solutions (0,0) and ( 17.75 , 14.75 ).

 

 



10)  

 11x -  7y = xy,       9x - 4y = 6xy

x = Answer: 13

y = Answer: 12


SOLUTION 1 :

This system is not linear in x and y as the product of variables x and y exists in the equations.

Also, note that if x = 0, then y=0 and vice versa, So,(0,0) is a solution for the system and any other solution would have both x ≠ 0.

Consider, 11x - 7y = xy.

Dividing by xy,

11y -   7x = 1

- 7x + 11y = 1 ...... (1)

Consider, 9x - 4y = 6xy

Dividing by xy.

- 4x + 9y = 6  ..... (2)

Put 1x = a , 1y = b in (1) and (2), we get

-7a + 11b = 1   ......    (3)

-4a + 9b = 6  ...... (4)

Now, (3) and (4) is a linear system in a and b.

Solving (3) and (4), we get

(3) x 4         -28a + 44b = 4

(4) x 7         -28a + 63b = 42

                                -19b = -38

                                  b = 3819

                                  b = 2.

Substituting b = 2 in (3).

-7a + 11(2) = 1.

-7a + 22 = 1

-7a = 1 - 22

-7a = -21

          a = 217

          a = 3

Hence a = 3  ⇒     x = 13

           b = 2   ⇒     y = 12 .

The system has two solutions (0,0) and ( 13 , 12 ).