SOLUTION: Find the center, vertices, foci, and asymtotes of the hyperbola 4x^2-y^2-8x+2Y-1=0 AND GRAPH Find the vertex, fous, and directrix of the parabola x^2-4x-4y+16=0 GRAPH

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Find the center, vertices, foci, and asymtotes of the hyperbola 4x^2-y^2-8x+2Y-1=0 AND GRAPH Find the vertex, fous, and directrix of the parabola x^2-4x-4y+16=0 GRAPH      Log On


   



Question 281903: Find the center, vertices, foci, and asymtotes of the hyperbola
4x^2-y^2-8x+2Y-1=0 AND GRAPH
Find the vertex, fous, and directrix of the parabola x^2-4x-4y+16=0 GRAPH

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
what are the slopes of the asymptotes of the hyperbola with equation
4x%5E2-y%5E2-8x%2B2y-1=0

First get it in standard form, which is either

%28x-h%29%5E2%2Fa%5E2-%28y-k%29%5E2%2Fb%5E2=1 if the hyperbola opens right and left, 

or

%28y-k%29%5E2%2Fa%5E2-%28x-h%29%5E2%2Fb%5E2=1 if the hyperbola opens upward and downward.

4x%5E2-y%5E2-8x%2B2y-1=0

Get the loose number -1 off the left side

4x%5E2-y%5E2-8x%2B2y=1

Get the x term next to the x%5E2 term.
Get the y term next to the y%5E2 term.

4x%5E2-8x-y%5E2%2B2y=1

Factor the coefficient of x%5E2 out of the 
first two terms on the left. 
Farctor the coefficient of y%5E2 out of the 
last two terms on the left. 

4%28x%5E2-2x%29-1%28y%5E2-2y%29=1

Complete the square on %28x%5E2-2x%29 by multiplying
the coefficient of x, which is -2 by 1%2F2 getting -1,
and then squaring -1, getting +1.  And we add that inside the
first parentheses.  However since there is a 4 in fromt of the
first parentheses, adding +1 inside the parentheses amounts
to adding +4*1 or +4 to the left side, so we must add +4 
to the right side:

4%28x%5E2-2x%2Bred%281%29%29-1%28y%5E2-2y%29=1%2Bred%284%29


Complete the square on %28y%5E2-2y%29 by multiplying
the coefficient of y, which is -2 by 1%2F2 getting -1,
and then squaring -1, getting +1.  And we add that inside the
second parentheses.  However since there is a -1 in fromt of the
second parentheses, adding +1 inside the parentheses amounts
to adding 1%2A-1 or -1 to the left side, so we must add -1 
to the right side:



Factor the parentheses as squares of binomials, and combine
the numbers on the right:

4%28x-1%29%5E2-%28y-1%29%5E2=4

Get a 1 on the right by dividing through by 4

4%28x-1%29%5E2%2F4-%28y-1%29%5E2%2F4=4%2F4

%28x-1%29%5E2%2F1-%28y-1%29%5E2%2F4=1

Since the variable x comes first in the standard form, the
hyperbola opens right and left.

So we compare that to:

%28x-h%29%5E2%2Fa%5E2-%28y-k%29%5E2%2Fb%5E2=1

The center is at (1,1).  So we plot the center:



a%5E2=1 so a=1, the semi-transverse axis is 1 unit
long, so we draw the complete transverse axis right and left
1 unit from the center, that is, the tranverse axis is the 
horizontal green line below:

 

The two vertices are the endpoints of the transverse axis, so the
vertices are the two points 

(0,1) and (2,1)


b%5E2=4 so b=2, the semi-conjugate axis is 2 units
long, so we draw the complete conjugate axis up and down
2 units from the center, that is, the conjugate axis is the 
vertical green line below:

 

Now we draw in the defining rectangle

 

Now we can draw the asymptotes which are the extended diagonals
of the defining rectangle:



and we can sketch in the hyperbola:

 

The slopes of the asymptotes are %22%22%2B-b%2Fa+=+%22%22%2B-+2%2F1=%22%22%2B-+2

They go through the point which is the center of the hyperbola (1,1)

y-y%5B1%5D=m%28x-x%5B1%5D%29

Using m=2

y-1=2%28x-1%29

y-1=2x-2

y=2x-1

Using m=-2

y-1=-2%28x-1%29

y-1=-2x%2B2

y=-2x%2B3

To find the foci. we find c using

c%5E2=a%5E2%2Bb%5E2
c%5E2=1%5E2%2B2%5E2
c%5E2=1%2B4
c%5E2=5
c=%22%22%2B-sqrt%285%29

The foci are c units right and left of the center:

They are (1-sqrt%285%29,1) and (1+sqrt%285%29,1)
-sqrt(5)
I'll draw the foci in:

  





Edwin