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If the sum of the slopes of the lines gi...

If the sum of the slopes of the lines given by `2x^(2)+kxy-3y^(2)=0` is equal to their product, then k=

A

`-2`

B

`2`

C

`(-2)/(3)`

D

`(-2)/(9)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( k \) such that the sum of the slopes of the lines represented by the equation \( 2x^2 + kxy - 3y^2 = 0 \) is equal to their product. ### Step-by-Step Solution: 1. **Start with the given equation**: \[ 2x^2 + kxy - 3y^2 = 0 \] 2. **Divide the entire equation by \( x^2 \)**: \[ 2 + \frac{ky}{x} - 3\left(\frac{y}{x}\right)^2 = 0 \] Let \( m = \frac{y}{x} \) (where \( m \) is the slope of the line). The equation becomes: \[ 2 + km - 3m^2 = 0 \] 3. **Rearrange the equation**: \[ -3m^2 + km + 2 = 0 \] This is a quadratic equation in terms of \( m \). 4. **Identify the coefficients**: The quadratic equation can be expressed as: \[ Am^2 + Bm + C = 0 \] where \( A = -3 \), \( B = k \), and \( C = 2 \). 5. **Use the formulas for the sum and product of the roots**: - The sum of the roots \( m_1 + m_2 \) is given by: \[ m_1 + m_2 = -\frac{B}{A} = -\frac{k}{-3} = \frac{k}{3} \] - The product of the roots \( m_1 m_2 \) is given by: \[ m_1 m_2 = \frac{C}{A} = \frac{2}{-3} = -\frac{2}{3} \] 6. **Set the sum equal to the product**: According to the problem, the sum of the slopes is equal to their product: \[ \frac{k}{3} = -\frac{2}{3} \] 7. **Solve for \( k \)**: Multiply both sides by 3: \[ k = -2 \] ### Final Answer: The value of \( k \) is \( -2 \).
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