SOLUTION: Please help me solve and graph this equation: {{{ 9x^2-4y^2+18x+32y-91=0 }}} I tried putting it in standard form and it ended up being a horizontal hyperbola. The standard form

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Please help me solve and graph this equation: {{{ 9x^2-4y^2+18x+32y-91=0 }}} I tried putting it in standard form and it ended up being a horizontal hyperbola. The standard form       Log On


   



Question 572346: Please help me solve and graph this equation: +9x%5E2-4y%5E2%2B18x%2B32y-91=0+
I tried putting it in standard form and it ended up being a horizontal hyperbola. The standard form was +%28x%2B2%29%5E2+%2F+7+-+4%28y%2B4%29%5E2+%2F+63+=+1+
From there I got the center of the hyperbola which is (h,k) or (-2,-4)and I graphed it. Then I looked for the values for a, b, and c. A was +sqrt+%28+7+%29+ or 2.6 as a decimal and B was +sqrt+%28+63+%29+ or 7.9 as a decimal. I graphed A and B as the conjugate and transverse axes. This is where I got confused. The equation for the hyperbola had x on the left and y on the right, meaning it should graph horizontally. But I graphed the axes and the hyperbola came out vertical. Please help me see where I went wrong!

Found 2 solutions by lwsshak3, KMST:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Solve and graph
9x^2-4y^2+18x+32y-91=0
complete the square
9(x^2+2x+1)-4(y^2-8y+16)=91+9-64=36
9(x+1)^2-4(y-4)^2=36
(x+1)^2/4-(y-4)^2/9=1
This is an equation of a hyperbola with horizontal transverse axis of the standard form: (x-h)^2/a^2-(y-k)^2/b^2=1, (h,k) being the (x,y) coordinates of the center.
..
For given equation:
Center:(-1,4)
a^2=4
a=2
..
b^2=9
b=3
..
slope of asymptotes=±b/a=±3/2
Equation of asymptotes:
y=mx+b
y=-3x/2+b
solving for b using (x,y) coordinates of center thru which the asymptote goes.
4=-(3*-1)/2+b
b=5/2
Equation:y=-3x/2+5/2
..
y=3x/2+b
solving for b using (x,y) coordinates of center thru which the asymptote goes.
4=(3*-1)/2+b
b=11/2
Equation:y=3x/2+11/2
..
see the graph below as a visual check on the above:
y=(2.25(x+1)^2-9)^.5+4

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
Here's how I go about it:
+9x%5E2-4y%5E2%2B18x%2B32y-91=0+ --> %289x%5E2%2B18x%29%2B%28-4y%5E2%2B32y%29-91=0 --> 9%28x%5E2%2B2x%29%2B%28-4%29%28y%5E2-8y%29-91=0 --> 9%28%28x%5E2%2B2x%2B1%29-1%29-4%28%28y%5E2-8y%2B16%29-16%29-91=0 --> 9%28%28x%2B1%29%5E2-1%29-4%28%28y-4%29%5E2-16%29-91=0 --> 9%28x%2B1%29%5E2-9-4%28y-4%29%5E2-4%28-16%29-91=0 --> 9%28x%2B1%29%5E2-4%28y-4%29%5E2-9%2B64-91=0 --> 9%28x%2B1%29%5E2-4%28y-4%29%5E2-36=0 --> 9%28x%2B1%29%5E2-4%28y-4%29%5E2=36
and dividing both sides by 36
%28x%2B1%29%5E2%2F4-%28y-4%29%5E2%2F9=1