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Mathematics 9 Online
OpenStudy (darkbluechocobo):

Help with putting conic equation into vertex form

OpenStudy (darkbluechocobo):

x2 + 9y2 + 10x − 18y + 25 = 0

OpenStudy (darkbluechocobo):

I know this is an ellipse

OpenStudy (darkbluechocobo):

And it is a horizontal ellipses as well

OpenStudy (anonymous):

complete the square twice it is a real pain

Nnesha (nnesha):

\[\huge\rm (x^2+10x)+(9y^2-8y)=-25\] complete the square left side

OpenStudy (anonymous):

\[x^2 + 9y^2 + 10x − 18y + 25 = 0 \\ x^2-10x+9y^2-18y=25\] is a start

OpenStudy (darkbluechocobo):

(x^2+10x) + (9y^2-18y)=-25

OpenStudy (anonymous):

x2 + 9y2 + 10x − 18y + 25 = 0 $$x^2+9y^2+10x-18y+25=(x^2+10x+25)+9(y^2+2y+1-1)\\\quad=(x+5)^2+9(y+1)^2-9$$

OpenStudy (anonymous):

factor out the 9 of the y term \[x^2+10x+9(y^2-2y)=-25\]

OpenStudy (darkbluechocobo):

(x+5)^2+9(y^2-2y)^2=-25

OpenStudy (anonymous):

er, that should be \(y^2-2y+1-1\) and then \((y-1)^2\)

Nnesha (nnesha):

b/2 = 10/2 take square of 5 add to the right side

OpenStudy (anonymous):

\[(x+5)^2+\overbrace{9(y^2-2y)^2}^{\text{mistake here}}=-25\]

OpenStudy (anonymous):

\[(x-5)^2+9(y-1)^2=-25+5^2+9\]

OpenStudy (darkbluechocobo):

so we are left with (x-5)^2 +9(y-1)^2=9?

OpenStudy (anonymous):

then divide by 9 to put in standard form

OpenStudy (anonymous):

i made a typo \(-5\) should be \(+5\) of course

Nnesha (nnesha):

it should equal to 1

OpenStudy (darkbluechocobo):

(x+5)^2+(y-1)^2=1

Nnesha (nnesha):

nope

OpenStudy (anonymous):

divide ALL by 9

Nnesha (nnesha):

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