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The vertex of the parabola : 4y^(2)+12x...

The vertex of the parabola : `4y^(2)+12x-20y+67=0` is :

A

`((5)/(2),(7)/(2))`

B

`((7)/(2),(5)/(2))`

C

`(-(7)/(2),(5)/(2))`

D

`(-(5)/(2),(7)/(2))`

Text Solution

AI Generated Solution

The correct Answer is:
To find the vertex of the parabola given by the equation \(4y^2 + 12x - 20y + 67 = 0\), we will follow these steps: ### Step 1: Rearrange the equation We start by rearranging the equation to group the \(y\) terms together: \[ 4y^2 - 20y + 12x + 67 = 0 \] ### Step 2: Move the \(x\) terms to the other side Next, we isolate the \(y\) terms on one side: \[ 4y^2 - 20y = -12x - 67 \] ### Step 3: Factor out the coefficient of \(y^2\) Now, we factor out the 4 from the left side: \[ 4(y^2 - 5y) = -12x - 67 \] ### Step 4: Complete the square for the \(y\) terms To complete the square for the expression \(y^2 - 5y\), we take half of the coefficient of \(y\) (which is \(-5\)), square it, and add/subtract it inside the parentheses: \[ y^2 - 5y + \left(\frac{5}{2}\right)^2 - \left(\frac{5}{2}\right)^2 = y^2 - 5y + \frac{25}{4} - \frac{25}{4} \] This gives us: \[ y^2 - 5y = \left(y - \frac{5}{2}\right)^2 - \frac{25}{4} \] ### Step 5: Substitute back into the equation Substituting this back into our equation gives: \[ 4\left(\left(y - \frac{5}{2}\right)^2 - \frac{25}{4}\right) = -12x - 67 \] Distributing the 4: \[ 4\left(y - \frac{5}{2}\right)^2 - 25 = -12x - 67 \] ### Step 6: Move the constant to the other side Now, we move \(-25\) to the right side: \[ 4\left(y - \frac{5}{2}\right)^2 = -12x - 67 + 25 \] This simplifies to: \[ 4\left(y - \frac{5}{2}\right)^2 = -12x - 42 \] ### Step 7: Divide by 4 To simplify further, we divide the entire equation by 4: \[ \left(y - \frac{5}{2}\right)^2 = -3x - \frac{21}{2} \] ### Step 8: Rewrite in vertex form We can rewrite this equation as: \[ \left(y - \frac{5}{2}\right)^2 = -3\left(x + \frac{7}{2}\right) \] ### Step 9: Identify the vertex Now, we can identify the vertex from the equation in the form \((y - k)^2 = -4a(x - h)\). Here, \(h = -\frac{7}{2}\) and \(k = \frac{5}{2}\). Thus, the vertex of the parabola is: \[ \left(-\frac{7}{2}, \frac{5}{2}\right) \] ### Final Answer The vertex of the parabola \(4y^2 + 12x - 20y + 67 = 0\) is \(\left(-\frac{7}{2}, \frac{5}{2}\right)\). ---
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