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The eccentricity of the conic 3x^(2)+4y^...

The eccentricity of the conic `3x^(2)+4y^(2)-6x-8y+4=0` is

A

`1/2`

B

`1//sqrt(2)`

C

`sqrt2`

D

none

Text Solution

AI Generated Solution

The correct Answer is:
To find the eccentricity of the conic given by the equation \(3x^2 + 4y^2 - 6x - 8y + 4 = 0\), we will first rewrite the equation in standard form. ### Step 1: Rearranging the equation We start with the equation: \[ 3x^2 + 4y^2 - 6x - 8y + 4 = 0 \] Rearranging gives: \[ 3x^2 - 6x + 4y^2 - 8y + 4 = 0 \] ### Step 2: Completing the square for \(x\) and \(y\) Next, we will complete the square for the \(x\) and \(y\) terms. **For \(x\):** \[ 3(x^2 - 2x) = 3((x - 1)^2 - 1) = 3(x - 1)^2 - 3 \] **For \(y\):** \[ 4(y^2 - 2y) = 4((y - 1)^2 - 1) = 4(y - 1)^2 - 4 \] ### Step 3: Substitute back into the equation Substituting these completed squares back into the equation gives: \[ 3((x - 1)^2 - 1) + 4((y - 1)^2 - 1) + 4 = 0 \] Simplifying this: \[ 3(x - 1)^2 - 3 + 4(y - 1)^2 - 4 + 4 = 0 \] \[ 3(x - 1)^2 + 4(y - 1)^2 - 3 = 0 \] \[ 3(x - 1)^2 + 4(y - 1)^2 = 3 \] ### Step 4: Divide by 3 to get standard form Dividing the entire equation by 3: \[ \frac{(x - 1)^2}{1} + \frac{(y - 1)^2}{\frac{3}{4}} = 1 \] ### Step 5: Identify the conic type This is the standard form of an ellipse: \[ \frac{(x - h)^2}{a^2} + \frac{(y - k)^2}{b^2} = 1 \] where \(h = 1\), \(k = 1\), \(a^2 = 1\), and \(b^2 = \frac{3}{4}\). ### Step 6: Calculate eccentricity The eccentricity \(e\) of an ellipse is given by: \[ e = \sqrt{1 - \frac{a^2}{b^2}} \] Here, \(a^2 = 1\) and \(b^2 = \frac{3}{4}\). Thus: \[ e = \sqrt{1 - \frac{1}{\frac{3}{4}}} = \sqrt{1 - \frac{4}{3}} = \sqrt{-\frac{1}{3}} \] Since \(e\) cannot be imaginary, we need to check our calculations. ### Step 7: Correct calculation of eccentricity We should actually use: \[ e = \sqrt{1 - \frac{b^2}{a^2}} \text{ (since } b > a \text{ for this ellipse)} \] So: \[ e = \sqrt{1 - \frac{\frac{3}{4}}{1}} = \sqrt{1 - \frac{3}{4}} = \sqrt{\frac{1}{4}} = \frac{1}{2} \] ### Final Answer The eccentricity of the conic is: \[ \boxed{\frac{1}{2}} \]
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