Scroll:Algebra new >> cross multipilication method >> ps (4122)


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)  

 Solve the following systems of equations using cross multipilication method. 

0.5x + 0.8y = 0.44 ;     0.8x + 0.6y = 0.5

X =    

Y  =  


Answer:_______________




2)  

 Solve the following systems of equations using cross multipilication method. 

9x + 12y = 72 ,     60x - 33y = 141

X =    

Y  =  


Answer:_______________




3)  

 Solve the following systems of equations using cross multipilication method. 

3x2 - 5y3 = 2 ;      x3 + y2 = 136

X =    

Y  =  


Answer:_______________




4)  

 Solve the following systems of equations using cross multipilication method. 

1x + 1.6y = 0.88 ;     1.6x + 1.2y = 1

X =    

Y  =  


Answer:_______________




5)  

 Solve the following systems of equations using cross multipilication method. 

3x + 4y = 24 ,     20x - 11y = 47

X =    

Y  =  


Answer:_______________




6)  

 Solve the following systems of equations using cross multipilication method. 

9x6 - 15y9 = 6 ;      x9 + y6 = 3918

X =    

Y  =  


Answer:_______________




7)  

 Solve the following systems of equations using cross multipilication method. 

1.5x + 2.4y = 1.32 ;     2.4x + 1.8y = 1.5

X =    

Y  =  


Answer:_______________




8)  

 Solve the following systems of equations using cross multipilication method. 

6x + 8y = 48 ,     40x - 22y = 94

X =    

Y  =  


Answer:_______________




9)  

 Solve the following systems of equations using cross multipilication method. 

6x4 - 10y6 = 4 ;      x6 + y4 = 2612

X =    

Y  =  


Answer:_______________




10)  

 Solve the following systems of equations using cross multipilication method. 

0.5x + 0.8y = 0.44 ;     0.8x + 0.6y = 0.5

X =    

Y  =  


Answer:_______________




 

1)  

 Solve the following systems of equations using cross multipilication method. 

0.5x + 0.8y = 0.44 ;     0.8x + 0.6y = 0.5

X =   Answer: 0.4 

Y  =   Answer: 0.3


SOLUTION 1 :

 solution:  

0.5x  + 0.8y - 0.44 = 0        ........(1)

          0.8x +  0.6y - 0.5 = 0        .........(2)

Here ,

a1 = 0.5, b1 = 0.8, c1 = - 0.44

a2 = 0.8,  b2 = 0.6,  c2 = - 0.5

a1b2 - a2b1 = 0.5(0.6) - 0.8 x 0.8

                      = - 0.3 - 0.64  = -0.34 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
0.8-0.440.50.8
0.6-0.50.80.6

 

We have 

0.8 x 0.5 = -0.4 , 0.6 x -0.44 = 0.264, 

-0.44 x 0.8 = -0.352,  -0.5 x 0.5 = -0.25

0.5 x 0.6 = -0.3, 0.8 x 0.8 = 0.64

 

 

 

x

---------

-0.4-0.264

=

y

---------

-0.352 - (-0.25)

=

1

---------

0.3 - 0.64

 

⇒      

x

---------

-0.136

=

y

---------

-0.352 + 0.25

=

1

-------

-0.34

 

 ⇒

x

---------

-0.136

=

y

---------

-0.102

=

1

-------

-0.34

 ⇒ 

x

------

-0.136

=

1

------

-0.34

 

x=

-0.136

----------

-0.34

 

x = 0.4

 

 

y

------

-0.102

=

1

------

-0.34

 

y=

-0.102

----------

-0.34

 

 

 

y =  0.3
 

Hence the solution is ( 0.4, 0.3 ).

 

 

 

 



2)  

 Solve the following systems of equations using cross multipilication method. 

9x + 12y = 72 ,     60x - 33y = 141

X =   Answer: 4 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

9x  + 12y - 72 = 0        ........(1)

          60x - 33y - 141 = 0        .........(2)

Here ,

a1 = 9, b1 = 12, c1 = - 72

a2 = 60,  b2 = 33,  c2 = - 141

a1b2 - a2b1 = 9(-33) - 60 x 12

                      = - 297 - 720  = -1017 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
12-72912
-33-14160-33

 

We have 

12 x -141 = -1692 , -33 x -72 = 2376, 

-72 x 60 = -4320,  -141 x 9 = -1269

9 x -33 = -297, 60 x 12 = 720

 

 

 

x

---------

-1692-2376

=

y

---------

-4320 - (-1269)

=

1

---------

-297 - 720

 

⇒      

x

---------

-4068

=

y

---------

-4320 + 1269

=

1

-------

-1017

 

 ⇒

x

---------

-4068

=

y

---------

-3051

=

1

-------

-1017

 ⇒ 

x

------

-4068

=

1

------

-1017

 

x=

-4068

----------

-1017

 

x = 4

 

 

y

------

-3051

=

1

------

-1017

 

y=

-3051

----------

-1017

 

 

 

y =  3
 

Hence the solution is ( 4, 3 ).

 

 

 

 



3)  

 Solve the following systems of equations using cross multipilication method. 

3x2 - 5y3 = 2 ;      x3 + y2 = 136

X =   Answer: 2 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

3x2 - 5y3 = -2

9x - 10y

--------

6

=-2

 

 9x - 10y = -12

 

9x  - 10y + 12 = 0        ........(1)

 

x3 + y2 = 136

 

2x + 3y

--------

6

=

13

-------

6

2x + 3y=

13

---------

6

x6

 

          3x +  2y - 13 = 0        .........(2)

Here ,

a1 = 9, b1 = -10, c1 =  12

a2 = 2,  b2 = 3,  c2 = - 13

a1b2 - a2b1 = (9x3) - (2 x 10)

                      =  27 + 20  = 47 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
-10129-10
3-1323

 

We have 

-10 x -13 = 130 , 3 x 12 = 36, 

12 x 2 = 24,  13 x 9 = 117

9 x 3 = 27, 2 x 10 = 20

 

 

 

x

------

130 - 36

=

y

---------

24 + 117

=

1

---------

27 + 20

 

⇒      

x

------

94

=

y

---------

24 + 117

=

1

-------

47

 

 ⇒

x

---------

94

=

y

---------

141

=

1

-------

47

 ⇒ 

x

------

94

=

1

------

47

 

x=

94

----------

47

 

x = 2

 

 

y

------

141

=

1

------

47

 

y=

141

----------

47

 

 

 

y =  3
 

Hence the solution is ( 2, 3 ).

 

 

 

 



4)  

 Solve the following systems of equations using cross multipilication method. 

1x + 1.6y = 0.88 ;     1.6x + 1.2y = 1

X =   Answer: 0.4 

Y  =   Answer: 0.3


SOLUTION 1 :

 solution:  

1x  + 1.6y - 0.88 = 0        ........(1)

          1.6x +  1.2y - 1 = 0        .........(2)

Here ,

a1 = 1, b1 = 1.6, c1 = - 0.88

a2 = 1.6,  b2 = 1.2,  c2 = - 1

a1b2 - a2b1 = 1(1.2) - 1.6 x 1.6

                      = - 1.2 - 2.56  = -1.36 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
1.6-0.8811.6
1.2-11.61.2

 

We have 

1.6 x 1 = -1.6 , 1.2 x -0.88 = 1.056, 

-0.88 x 1.6 = -1.408,  -1 x 1 = -1

1 x 1.2 = -1.2, 1.6 x 1.6 = 2.56

 

 

 

x

---------

-1.6-1.056

=

y

---------

-1.408 - (-1)

=

1

---------

1.2 - 2.56

 

⇒      

x

---------

-0.544

=

y

---------

-1.408 + 1

=

1

-------

-1.36

 

 ⇒

x

---------

-0.544

=

y

---------

-0.408

=

1

-------

-1.36

 ⇒ 

x

------

-0.544

=

1

------

-1.36

 

x=

-0.544

----------

-1.36

 

x = 0.4

 

 

y

------

-0.408

=

1

------

-1.36

 

y=

-0.408

----------

-1.36

 

 

 

y =  0.3
 

Hence the solution is ( 0.4, 0.3 ).

 

 

 

 



5)  

 Solve the following systems of equations using cross multipilication method. 

3x + 4y = 24 ,     20x - 11y = 47

X =   Answer: 4 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

3x  + 4y - 24 = 0        ........(1)

          20x - 11y - 47 = 0        .........(2)

Here ,

a1 = 3, b1 = 4, c1 = - 24

a2 = 20,  b2 = 11,  c2 = - 47

a1b2 - a2b1 = 3(-11) - 20 x 4

                      = - 33 - 80  = -113 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
4-2434
-11-4720-11

 

We have 

4 x -47 = -188 , -11 x -24 = 264, 

-24 x 20 = -480,  -47 x 3 = -141

3 x -11 = -33, 20 x 4 = 80

 

 

 

x

---------

-188-264

=

y

---------

-480 - (-141)

=

1

---------

-33 - 80

 

⇒      

x

---------

-452

=

y

---------

-480 + 141

=

1

-------

-113

 

 ⇒

x

---------

-452

=

y

---------

-339

=

1

-------

-113

 ⇒ 

x

------

-452

=

1

------

-113

 

x=

-452

----------

-113

 

x = 4

 

 

y

------

-339

=

1

------

-113

 

y=

-339

----------

-113

 

 

 

y =  3
 

Hence the solution is ( 4, 3 ).

 

 

 

 



6)  

 Solve the following systems of equations using cross multipilication method. 

9x6 - 15y9 = 6 ;      x9 + y6 = 3918

X =   Answer: 2 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

9x6 - 15y9 = -6

81x - 90y

--------

18

=-6

 

 81x - 90y = -108

 

81x  - 90y + 108 = 0        ........(1)

 

x9 + y6 = 3918

 

6x + 9y

--------

18

=

39

-------

18

6x + 9y=

39

---------

54

x6

 

          9x +  6y - 39 = 0        .........(2)

Here ,

a1 = 81, b1 = -90, c1 =  108

a2 = 6,  b2 = 9,  c2 = - 39

a1b2 - a2b1 = (81x9) - (6 x 90)

                      =  729 + 540  = 1269 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
-9010881-90
9-3969

 

We have 

-90 x -39 = 3510 , 9 x 108 = 972, 

108 x 6 = 648,  39 x 81 = 3159

81 x 9 = 729, 6 x 90 = 540

 

 

 

x

------

3510 - 972

=

y

---------

648 + 3159

=

1

---------

729 + 540

 

⇒      

x

------

2538

=

y

---------

648 + 3159

=

1

-------

1269

 

 ⇒

x

---------

2538

=

y

---------

3807

=

1

-------

1269

 ⇒ 

x

------

2538

=

1

------

1269

 

x=

2538

----------

1269

 

x = 2

 

 

y

------

3807

=

1

------

1269

 

y=

3807

----------

1269

 

 

 

y =  3
 

Hence the solution is ( 2, 3 ).

 

 

 

 



7)  

 Solve the following systems of equations using cross multipilication method. 

1.5x + 2.4y = 1.32 ;     2.4x + 1.8y = 1.5

X =   Answer: 0.4 

Y  =   Answer: 0.3


SOLUTION 1 :

 solution:  

1.5x  + 2.4y - 1.32 = 0        ........(1)

          2.4x +  1.8y - 1.5 = 0        .........(2)

Here ,

a1 = 1.5, b1 = 2.4, c1 = - 1.32

a2 = 2.4,  b2 = 1.8,  c2 = - 1.5

a1b2 - a2b1 = 1.5(1.8) - 2.4 x 2.4

                      = - 2.7 - 5.76  = -3.06 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
2.4-1.321.52.4
1.8-1.52.41.8

 

We have 

2.4 x 1.5 = -3.6 , 1.8 x -1.32 = 2.376, 

-1.32 x 2.4 = -3.168,  -1.5 x 1.5 = -2.25

1.5 x 1.8 = -2.7, 2.4 x 2.4 = 5.76

 

 

 

x

---------

-3.6-2.376

=

y

---------

-3.168 - (-2.25)

=

1

---------

2.7 - 5.76

 

⇒      

x

---------

-1.224

=

y

---------

-3.168 + 2.25

=

1

-------

-3.06

 

 ⇒

x

---------

-1.224

=

y

---------

-0.918

=

1

-------

-3.06

 ⇒ 

x

------

-1.224

=

1

------

-3.06

 

x=

-1.224

----------

-3.06

 

x = 0.4

 

 

y

------

-0.918

=

1

------

-3.06

 

y=

-0.918

----------

-3.06

 

 

 

y =  0.3
 

Hence the solution is ( 0.4, 0.3 ).

 

 

 

 



8)  

 Solve the following systems of equations using cross multipilication method. 

6x + 8y = 48 ,     40x - 22y = 94

X =   Answer: 4 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

6x  + 8y - 48 = 0        ........(1)

          40x - 22y - 94 = 0        .........(2)

Here ,

a1 = 6, b1 = 8, c1 = - 48

a2 = 40,  b2 = 22,  c2 = - 94

a1b2 - a2b1 = 6(-22) - 40 x 8

                      = - 132 - 320  = -452 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
8-4868
-22-9440-22

 

We have 

8 x -94 = -752 , -22 x -48 = 1056, 

-48 x 40 = -1920,  -94 x 6 = -564

6 x -22 = -132, 40 x 8 = 320

 

 

 

x

---------

-752-1056

=

y

---------

-1920 - (-564)

=

1

---------

-132 - 320

 

⇒      

x

---------

-1808

=

y

---------

-1920 + 564

=

1

-------

-452

 

 ⇒

x

---------

-1808

=

y

---------

-1356

=

1

-------

-452

 ⇒ 

x

------

-1808

=

1

------

-452

 

x=

-1808

----------

-452

 

x = 4

 

 

y

------

-1356

=

1

------

-452

 

y=

-1356

----------

-452

 

 

 

y =  3
 

Hence the solution is ( 4, 3 ).

 

 

 

 



9)  

 Solve the following systems of equations using cross multipilication method. 

6x4 - 10y6 = 4 ;      x6 + y4 = 2612

X =   Answer: 2 

Y  =   Answer: 3


SOLUTION 1 :

 solution:  

6x4 - 10y6 = -4

36x - 40y

--------

12

=-4

 

 36x - 40y = -48

 

36x  - 40y + 48 = 0        ........(1)

 

x6 + y4 = 2612

 

4x + 6y

--------

12

=

26

-------

12

4x + 6y=

26

---------

24

x6

 

          6x +  4y - 26 = 0        .........(2)

Here ,

a1 = 36, b1 = -40, c1 =  48

a2 = 4,  b2 = 6,  c2 = - 26

a1b2 - a2b1 = (36x6) - (4 x 40)

                      =  216 + 160  = 376 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
-404836-40
6-2646

 

We have 

-40 x -26 = 1040 , 6 x 48 = 288, 

48 x 4 = 192,  26 x 36 = 936

36 x 6 = 216, 4 x 40 = 160

 

 

 

x

------

1040 - 288

=

y

---------

192 + 936

=

1

---------

216 + 160

 

⇒      

x

------

752

=

y

---------

192 + 936

=

1

-------

376

 

 ⇒

x

---------

752

=

y

---------

1128

=

1

-------

376

 ⇒ 

x

------

752

=

1

------

376

 

x=

752

----------

376

 

x = 2

 

 

y

------

1128

=

1

------

376

 

y=

1128

----------

376

 

 

 

y =  3
 

Hence the solution is ( 2, 3 ).

 

 

 

 



10)  

 Solve the following systems of equations using cross multipilication method. 

0.5x + 0.8y = 0.44 ;     0.8x + 0.6y = 0.5

X =   Answer: 0.4 

Y  =   Answer: 0.3


SOLUTION 1 :

 solution:  

0.5x  + 0.8y - 0.44 = 0        ........(1)

          0.8x +  0.6y - 0.5 = 0        .........(2)

Here ,

a1 = 0.5, b1 = 0.8, c1 = - 0.44

a2 = 0.8,  b2 = 0.6,  c2 = - 0.5

a1b2 - a2b1 = 0.5(0.6) - 0.8 x 0.8

                      = - 0.3 - 0.64  = -0.34 ≈ 0.

Thus, the system has a unique solutions.

Consider,

xy 1
0.8-0.440.50.8
0.6-0.50.80.6

 

We have 

0.8 x 0.5 = -0.4 , 0.6 x -0.44 = 0.264, 

-0.44 x 0.8 = -0.352,  -0.5 x 0.5 = -0.25

0.5 x 0.6 = -0.3, 0.8 x 0.8 = 0.64

 

 

 

x

---------

-0.4-0.264

=

y

---------

-0.352 - (-0.25)

=

1

---------

0.3 - 0.64

 

⇒      

x

---------

-0.136

=

y

---------

-0.352 + 0.25

=

1

-------

-0.34

 

 ⇒

x

---------

-0.136

=

y

---------

-0.102

=

1

-------

-0.34

 ⇒ 

x

------

-0.136

=

1

------

-0.34

 

x=

-0.136

----------

-0.34

 

x = 0.4

 

 

y

------

-0.102

=

1

------

-0.34

 

y=

-0.102

----------

-0.34

 

 

 

y =  0.3
 

Hence the solution is ( 0.4, 0.3 ).