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The general equation of a hyperbola is 36x2 - 9y2 - 24x + 54y - 113 = 0. Write the equation of this hyperbola in standard form and give the coordinates of the center, the coordinates of the vertices, and the equations of the asymptotes.

I did learn how to solve these equations, but I can't get past putting these into S.F.

 Mar 17, 2016

Best Answer 

 #1
avatar+128475 
+10

36x2 - 9y2 - 24x + 54y - 113 = 0     add 113 to each side

 

36x^2 - 9y^2 - 24x + 54y  = 113      complete the square on x and y

 

36 [x^2 - (2/3)x + 1/9] - 9 [y^2 - 6y + 9]  = 113 + 4 - 81    factor and simplify

 

36(x - 1/3)^2  - 9 (y - 3)^2  = 36        divide both sides by 36

 

( x - 1/3)^2         -     (y - 3)^2     =     1

      1                            4

 

That's SF, Shades.....I think what may be giving you problems is completing the square, particulalrly when the lead coefficient isn't = 1.......here's a resource that might help.......http://regentsprep.org/Regents/math/algtrig/ATE3/quadcompletesquare.htm

 

Center = (1/3, 3)

 

Vertices =  [x coordinate of the center ± √ [c^2 - b^2] , y coordinate of the center ]

 

In this case  c =  √5    and b =  2        so   c^2  = 5     and b^2   = 4

 

  [  1/3 ± √[5 - 4] , 3 ]    =  [  1/3 + 1 , 3]  and [ 1/3 -1, 3]      =   [ 4/3, 3]   and [-2/3, 3]

 

Asymptotes

 

y = ± 2/1 (x - 1/3) + 3

 

y = ± 2( x - 1/3) + 3

 

y = 2x -2/3 + 3           and      y = -2x + 2/3 + 3

 

y = 2x + 7/3              and      y = -2x + 11/3

 

Here's the graph with the pertinent info, Shades :   https://www.desmos.com/calculator/l7ew2an7qj         

 

 

 

 

cool cool cool

 Mar 17, 2016
 #1
avatar+128475 
+10
Best Answer

36x2 - 9y2 - 24x + 54y - 113 = 0     add 113 to each side

 

36x^2 - 9y^2 - 24x + 54y  = 113      complete the square on x and y

 

36 [x^2 - (2/3)x + 1/9] - 9 [y^2 - 6y + 9]  = 113 + 4 - 81    factor and simplify

 

36(x - 1/3)^2  - 9 (y - 3)^2  = 36        divide both sides by 36

 

( x - 1/3)^2         -     (y - 3)^2     =     1

      1                            4

 

That's SF, Shades.....I think what may be giving you problems is completing the square, particulalrly when the lead coefficient isn't = 1.......here's a resource that might help.......http://regentsprep.org/Regents/math/algtrig/ATE3/quadcompletesquare.htm

 

Center = (1/3, 3)

 

Vertices =  [x coordinate of the center ± √ [c^2 - b^2] , y coordinate of the center ]

 

In this case  c =  √5    and b =  2        so   c^2  = 5     and b^2   = 4

 

  [  1/3 ± √[5 - 4] , 3 ]    =  [  1/3 + 1 , 3]  and [ 1/3 -1, 3]      =   [ 4/3, 3]   and [-2/3, 3]

 

Asymptotes

 

y = ± 2/1 (x - 1/3) + 3

 

y = ± 2( x - 1/3) + 3

 

y = 2x -2/3 + 3           and      y = -2x + 2/3 + 3

 

y = 2x + 7/3              and      y = -2x + 11/3

 

Here's the graph with the pertinent info, Shades :   https://www.desmos.com/calculator/l7ew2an7qj         

 

 

 

 

cool cool cool

CPhill Mar 17, 2016
 #2
avatar+466 
0

Just one question, what is c? How did you get c = square root of 5?

Shades  Mar 21, 2016
 #3
avatar+128475 
+5

Sorry, Shades...I made this a little more complicated than I should have.....c is the focal distance  = sqrt(5)  = sqrt [ a^2 + b^2]   = sqrt [1^2 + 2^2] = sqrt [1 + 4 ]  = c

 

So,  sqrt [c^2 - b^2]  is  just = a   ......which, in this case = 1

 

So...I should have simplified the location of the vertices as

 

[ h + a , k ]   and [ h - a,  k]   where h = 1/3 and k = 3 and a = 1 

 

So....we get he same result as I gave originally

 

The vertices are located at

 

[1/3 + 1 , 3 ]   and  [ 1/3  - 1, 3]     which simpliy to

 

[4/3 , 3 ]   and   [ -2/3, 3 ]    as before

 

 

Sorry for the "overkill"

 

 

 

cool cool cool

 Mar 21, 2016
 #4
avatar+466 
0

Thank you very much! cool

Shades  Mar 21, 2016

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