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Find the vertex, focus, equation of dire...

Find the vertex, focus, equation of directrix and axis, of parabolas
`3x^(2)-9x+5y`

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To find the vertex, focus, equation of directrix, and axis of the parabola given by the equation \(3x^2 - 9x + 5y = 0\), we will follow these steps: ### Step 1: Rearrange the Equation We start with the equation: \[ 3x^2 - 9x + 5y = 0 \] Rearranging gives: \[ 5y = -3x^2 + 9x \] or \[ y = -\frac{3}{5}x^2 + \frac{9}{5}x \] ### Step 2: Complete the Square Next, we will complete the square for the \(x\) terms: \[ y = -\frac{3}{5}(x^2 - 3x) \] To complete the square inside the parentheses, we take half of the coefficient of \(x\) (which is \(-3\)), square it, and add/subtract it: \[ y = -\frac{3}{5}\left(x^2 - 3x + \frac{9}{4} - \frac{9}{4}\right) \] This simplifies to: \[ y = -\frac{3}{5}\left((x - \frac{3}{2})^2 - \frac{9}{4}\right) \] Distributing the \(-\frac{3}{5}\): \[ y = -\frac{3}{5}(x - \frac{3}{2})^2 + \frac{27}{20} \] ### Step 3: Identify Vertex The vertex form of the parabola is: \[ y = a(x - h)^2 + k \] From our equation, we identify: - \(h = \frac{3}{2}\) - \(k = \frac{27}{20}\) Thus, the vertex is: \[ \text{Vertex} = \left(\frac{3}{2}, \frac{27}{20}\right) \] ### Step 4: Find Focus and Directrix The standard form of a parabola that opens downwards is: \[ y = -\frac{1}{4b}(x - h)^2 + k \] Here, we have: \[ -\frac{3}{5} = -\frac{1}{4b} \implies 4b = \frac{5}{3} \implies b = \frac{5}{12} \] The focus is located at: \[ \left(h, k - b\right) = \left(\frac{3}{2}, \frac{27}{20} - \frac{5}{12}\right) \] To compute \(k - b\), we need a common denominator (60): \[ \frac{27}{20} = \frac{81}{60}, \quad \frac{5}{12} = \frac{25}{60} \] Thus, \[ k - b = \frac{81}{60} - \frac{25}{60} = \frac{56}{60} = \frac{14}{15} \] So, the coordinates of the focus are: \[ \text{Focus} = \left(\frac{3}{2}, \frac{14}{15}\right) \] ### Step 5: Equation of the Directrix The equation of the directrix is given by: \[ y = k + b = \frac{27}{20} + \frac{5}{12} \] Again, using a common denominator (60): \[ \frac{27}{20} = \frac{81}{60}, \quad \frac{5}{12} = \frac{25}{60} \] Thus, \[ y = \frac{81}{60} + \frac{25}{60} = \frac{106}{60} = \frac{53}{30} \] So, the equation of the directrix is: \[ \text{Directrix: } y = \frac{53}{30} \] ### Step 6: Axis of the Parabola The axis of the parabola is the vertical line that passes through the vertex, given by: \[ x = \frac{3}{2} \] ### Summary of Results - **Vertex**: \(\left(\frac{3}{2}, \frac{27}{20}\right)\) - **Focus**: \(\left(\frac{3}{2}, \frac{14}{15}\right)\) - **Equation of Directrix**: \(y = \frac{53}{30}\) - **Axis**: \(x = \frac{3}{2}\)
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