Solving equation systems part three



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Solving equation systems part three



Solve {x + y = 4, 4xy = 15}.

x + y = 4

4xy = 15

y = 4 - x

4x(4 - x) = 15

4x² - 16x + 15 = 0

(2x - 3)(2x - 5) = 0

x = 3 / 2; 5 / 2

y = 4 - (3 / 2); 4 - (5 / 2)

y = 5 / 2; 3 / 2

solutions as (3 / 2, 5 / 2) and (5 / 2, 3 / 2)

x + y = 4 and 4xy = 15 cutting each other at (3 / 2, 5 / 2) and (5 / 2, 3 / 2)

 

Solve {6x + 6y = 19, 2xy = 5}.

6x + 6y = 19

2xy = 5

6y = 19 - 6x

y = (19 - 6x) / 6

2x(19 - 6x) / 6 = 5

6x² - 19x + 15 = 0

(2x - 3)(3x - 5) = 0

x = 3 / 2; 5 / 3

y = {19 - 6(3 / 2)} / 6; {19 - 6(5 / 3)} / 6

y = 5 / 3; 3 / 2

solutions as (3 / 2, 5 / 3) and (5 / 3, 3 / 2)

6x + 6y = 19 and 2xy = 5 cutting each other at (3 / 2, 5 / 3) and (5 / 3, 3 / 2)

 

Solve {6x + 6y = 25, 6xy = 25}.

6x + 6y = 25

6xy = 25

6y = 25 - 6x

y = (25 - 6x) / 6

6x(25 - 6x) / 6 = 25

6x² - 25x + 25 = 0

(2x - 5)(3x - 5) = 0

x = 5 / 2; 5 / 3

y = {25 - 6(5 / 2)} / 6; {25 - 6(5 / 3)} / 6

y = 5 / 3; 5 / 2

solutions as (5 / 3, 5 / 2) and (5 / 2, 5 / 3)

6x + 6y = 25 and 6xy = 25 cutting each other at (5 / 3, 5 / 2) and (5 / 2, 5 / 3)

 

Solve {15x + 15y = 16, 15xy = 4}.

15x + 15y = 16

15xy = 4

15y = 16 - 15x

y = (16 - 15x) / 15

15x(16 - 15x) / 15 = 4

15x² - 16x + 4 = 0

(3x - 2)(5x - 2) = 0

x = 2 / 3; 2 / 5

y = {16 - 15(2 / 3)} / 15; {16 - 15(2 / 5)} / 15

y = 2 / 5; 2 / 3

solutions as (2 / 5, 2 / 3) and (2 / 3, 2 / 5)

15x + 15y = 16 and 15xy = 4 cutting each other at (2 / 5, 2 / 3) and (2 / 3, 2 / 5)

 

Solve {15x + 15y = 19, 5xy = 2}.

15x + 15y = 19

5xy = 2

15y = 19 - 15x

y = (19 - 15x) / 15

5x(19 - 15x) / 15 = 2

15x² - 19x + 6 = 0

(3x - 2)(5x - 3) = 0

x = 2 / 3; 3 / 5

y = {19 - 15(2 / 3)} / 15; {19 - 15(3 / 5)} / 15

y = 3 / 5; 2 / 3

solutions as (3 / 5, 2 / 3) and (2 / 3, 3 / 5)

15x + 15y = 19 and 5xy = 2 cutting each other at (3 / 5, 2 / 3) and (2 / 3, 3 / 5)

 

Solve {x + y = 1, 25xy = 6}.

x + y = 1

25xy = 6

y = 1 - x

25x(1 - x) = 6

25x² - 25x + 6 = 0

(5x - 2)(5x - 3) = 0

x = 2 / 5; 3 / 5

y = 1 - (2 / 5); 1 - (3 / 5)

y = 3 / 5; 2 / 5

solutions as (2 / 5, 3 / 5) and (3 / 5, 2 / 5)

x + y = 1 and 25xy = 6 cutting each other at (2 / 5, 3 / 5) and (3 / 5, 2 / 5)


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0 user (users) favorited this work
  • View Count:266
  • Rating:General - Intended for all ages.
  • Publish Time:2021-12-02 08:38