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\( 4 ( x ^ { 2 } - 2 x ) + ( y ^ { 2 } + 4 y ) = 8 \)

Ask by Matthews Barker. in Singapore
Jan 22,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

The equation simplifies to an ellipse centered at (1, -2) with a semi-major axis of 4 units along the y-axis and a semi-minor axis of 2 units along the x-axis.

Solution

Certainly! Let's analyze and manipulate the given equation step by step. **Given Equation:** \[ 4(x^{2} - 2x) + (y^{2} + 4y) = 8 \] **Objective:** - Rewrite the equation in standard form by completing the squares. - Identify the type of conic section represented by the equation. ### Step 1: Complete the Square for the \( x \)-Terms Start with the \( x \)-terms: \[ 4(x^{2} - 2x) \] 1. **Factor out the coefficient of \( x^2 \):** \[ 4(x^{2} - 2x) = 4\left[ x^{2} - 2x \right] \] 2. **Complete the square inside the parentheses:** \[ x^{2} - 2x = \left( x^{2} - 2x + 1 \right) - 1 = (x - 1)^2 - 1 \] 3. **Multiply back by 4:** \[ 4\left[ (x - 1)^2 - 1 \right] = 4(x - 1)^2 - 4 \] ### Step 2: Complete the Square for the \( y \)-Terms Now, address the \( y \)-terms: \[ y^{2} + 4y \] 1. **Complete the square:** \[ y^{2} + 4y = \left( y^{2} + 4y + 4 \right) - 4 = (y + 2)^2 - 4 \] ### Step 3: Substitute Back into the Original Equation Replace the completed squares into the original equation: \[ 4(x - 1)^2 - 4 + (y + 2)^2 - 4 = 8 \] Combine like terms: \[ 4(x - 1)^2 + (y + 2)^2 - 8 = 8 \] Add 8 to both sides: \[ 4(x - 1)^2 + (y + 2)^2 = 16 \] ### Step 4: Divide to Obtain the Standard Form Divide every term by 16 to normalize the equation: \[ \frac{4(x - 1)^2}{16} + \frac{(y + 2)^2}{16} = \frac{16}{16} \] \[ \frac{(x - 1)^2}{4} + \frac{(y + 2)^2}{16} = 1 \] ### Step 5: Identify the Conic Section The standard form of the equation is: \[ \frac{(x - h)^2}{a^2} + \frac{(y - k)^2}{b^2} = 1 \] Comparing, we have: - \( h = 1 \) - \( k = -2 \) - \( a^2 = 4 \) ⇒ \( a = 2 \) - \( b^2 = 16 \) ⇒ \( b = 4 \) **Conclusion:** - The equation represents an **ellipse**. - **Center** of the ellipse: \( (1, -2) \). - **Semi-major axis** (along the \( y \)-axis): 4 units. - **Semi-minor axis** (along the \( x \)-axis): 2 units. **Graphical Representation:** ![Ellipse](https://i.imgur.com/ellipse.png) *Note: The image is a placeholder. In practice, you would plot the ellipse centered at (1, -2) with the specified axes lengths.* ### Summary By completing the squares for both \( x \) and \( y \), the original equation is transformed into the standard form of an ellipse: \[ \frac{(x - 1)^2}{4} + \frac{(y + 2)^2}{16} = 1 \] This reveals the geometric properties of the ellipse, including its center and axis lengths.

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The Deep Dive

To solve the equation \( 4 ( x ^ { 2 } - 2 x ) + ( y ^ { 2 } + 4 y ) = 8 \), we can start by simplifying it. Distribute the \( 4 \) in the first term to get \( 4x^2 - 8x + y^2 + 4y = 8 \). Rearranging gives us \( 4x^2 - 8x + y^2 + 4y - 8 = 0 \). Next, we can complete the square for the \( x \) and \( y \) terms. For \( x \), we take \( 4(x^2 - 2x) \) and complete the square to \( 4((x - 1)^2 - 1) = 4(x - 1)^2 - 4 \). For \( y \), \( y^2 + 4y \) can be rewritten as \((y + 2)^2 - 4\). Putting it all together gives us \( 4(x - 1)^2 - 4 + (y + 2)^2 - 4 = 0 \) or \( 4(x - 1)^2 + (y + 2)^2 = 8 \), which simplifies to \( (x - 1)^2 + \frac{(y + 2)^2}{4} = 1 \). This describes an ellipse centered at \( (1, -2) \). Now, if you're curious about the nature of this ellipse, it has a semi-major axis of \( 2 \) along the \( y \)-direction and a semi-minor axis of \( 1 \) along the \( x \)-direction. This means it stretches twice as far vertically than it does horizontally! And speaking of ellipses, did you know that they're not just beautiful shapes? They've been used in various real-world applications, from the orbits of planets to the design of certain musical instruments! Their unique geometry allows for interesting acoustic properties, making them a fun study in both math and physics.

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