Home
Class 12
MATHS
If the value of K, is the points (k, 2-2...

If the value of K, is the points (k, 2-2k), (1-k, 2k) and (-4-k, 6-2 k) are collinear.

Text Solution

AI Generated Solution

The correct Answer is:
To determine the value of \( k \) for which the points \( (k, 2-2k) \), \( (1-k, 2k) \), and \( (-4-k, 6-2k) \) are collinear, we can use the concept that the area of the triangle formed by three collinear points is zero. ### Step-by-Step Solution: 1. **Set up the Area Formula**: The area \( A \) of the triangle formed by the points \( (x_1, y_1) \), \( (x_2, y_2) \), and \( (x_3, y_3) \) can be calculated using the determinant: \[ A = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| \] For our points, we have: - \( (x_1, y_1) = (k, 2-2k) \) - \( (x_2, y_2) = (1-k, 2k) \) - \( (x_3, y_3) = (-4-k, 6-2k) \) 2. **Substituting the Points into the Area Formula**: Substitute the coordinates into the area formula: \[ A = \frac{1}{2} \left| k(2k - (6 - 2k)) + (1-k)((6 - 2k) - (2 - 2k)) + (-4-k)((2 - 2k) - 2k) \right| \] 3. **Simplifying the Expression**: Now simplify each term: - First term: \[ k(2k - 6 + 2k) = k(4k - 6) = 4k^2 - 6k \] - Second term: \[ (1-k)(6 - 2k - 2 + 2k) = (1-k)(4) = 4 - 4k \] - Third term: \[ (-4-k)(2 - 2k - 2k) = (-4-k)(2 - 4k) = -8 + 16k - 2k^2 + 4k = -8 + 20k - 2k^2 \] 4. **Combining All Terms**: Combine all the terms: \[ A = \frac{1}{2} \left| (4k^2 - 6k) + (4 - 4k) + (-8 + 20k - 2k^2) \right| \] Simplifying this gives: \[ A = \frac{1}{2} \left| (4k^2 - 2k^2) + (-6k - 4k + 20k) + (4 - 8) \right| \] \[ = \frac{1}{2} \left| 2k^2 + 10k - 4 \right| \] 5. **Setting the Area to Zero**: Since the points are collinear, set the area to zero: \[ \left| 2k^2 + 10k - 4 \right| = 0 \] This implies: \[ 2k^2 + 10k - 4 = 0 \] 6. **Solving the Quadratic Equation**: Divide the entire equation by 2: \[ k^2 + 5k - 2 = 0 \] Now apply the quadratic formula \( k = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): \[ k = \frac{-5 \pm \sqrt{5^2 - 4 \cdot 1 \cdot (-2)}}{2 \cdot 1} = \frac{-5 \pm \sqrt{25 + 8}}{2} = \frac{-5 \pm \sqrt{33}}{2} \] ### Final Values of \( k \): Thus, the values of \( k \) for which the points are collinear are: \[ k = \frac{-5 + \sqrt{33}}{2} \quad \text{and} \quad k = \frac{-5 - \sqrt{33}}{2} \]
Promotional Banner

Topper's Solved these Questions

  • DETERMINANTS

    NAGEEN PRAKASHAN ENGLISH|Exercise Exercise 4d|13 Videos
  • DETERMINANTS

    NAGEEN PRAKASHAN ENGLISH|Exercise Exercise 4e|4 Videos
  • DETERMINANTS

    NAGEEN PRAKASHAN ENGLISH|Exercise Exercise 4b|23 Videos
  • Continuity and Differentiability

    NAGEEN PRAKASHAN ENGLISH|Exercise Miscellaneous Exercise|23 Videos
  • DIFFERENTIAL EQUATIONS

    NAGEEN PRAKASHAN ENGLISH|Exercise Miscellaneous Exercise|18 Videos

Similar Questions

Explore conceptually related problems

For what value of k are the points (k ,2-2k) (k+1,2k) and (-4-k ,6-2k) are collinear?

For what value of k are the points (k ,2-2k)(-k+1,2k)a n d(-4-k ,6-2k) are collinear?

For what value of k are the points (k ,2-2k),(-k+1,2k)a n d(-4-k ,6-2k) collinear?

Find the values of k, if the points A (k+1,2k) ,B (3k,2k+3) and C (5k-1,5k) are collinear.

Find the value of k , if the points A(7,\ -2),\ \ B(5,\ 1) and C(3,\ 2k) are collinear.

If the points (5, 2, 4), (6, -1, 2) and (8, -7, k) are collinear, then k =

Find the value of k if the points A(2,\ 3),\ B(4,\ k)\ a n d\ C(6,\ 3) are collinear.

(i) If the points (1,4),(3,-2)and (k,1) are collinear, fine the value of k. (ii) If the points A(k+1,2k),B(3k,2k+3)andC(5k-1,5k) are collinear, then find k

The points (K, 3), (2, -4) and (-K+1,-2) are collinear. Find K.

Find the value of k if points (k ,\ 3),\ (6,\ -2) and (-3,\ 4) are collinear.