Math Problem Statement

Déterminer la valeur de x pour que les vecteurs AB et CD soient colinéaires, où A(-7, -8), B(-2, -4), C(-6, 4), et D(4, x).

Solution

The problem asks to determine the value of xx so that the vectors AB\overrightarrow{AB} and CD\overrightarrow{CD} are collinear, where the points are:

  • A(7,8)A(-7, -8)
  • B(2,4)B(-2, -4)
  • C(6,4)C(-6, 4)
  • D(4,x)D(4, x)

Solution:

1. Find the coordinates of the vectors AB\overrightarrow{AB} and CD\overrightarrow{CD}:

  • AB=BA=(2(7),4(8))=(5,4)\overrightarrow{AB} = B - A = (-2 - (-7), -4 - (-8)) = (5, 4)
  • CD=DC=(4(6),x4)=(10,x4)\overrightarrow{CD} = D - C = (4 - (-6), x - 4) = (10, x - 4)

2. Condition for collinearity:

Two vectors (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) are collinear if their components satisfy: x1x2=y1y2\frac{x_1}{x_2} = \frac{y_1}{y_2} This is equivalent to: x1y2=x2y1x_1 \cdot y_2 = x_2 \cdot y_1

For AB\overrightarrow{AB} and CD\overrightarrow{CD}, this becomes: 5(x4)=4105 \cdot (x - 4) = 4 \cdot 10


3. Solve the equation:

5(x4)=405(x - 4) = 40 5x20=405x - 20 = 40 5x=605x = 60 x=12x = 12


Final Answer:

The value of xx is 12.


Would you like me to provide more details or explore another related concept?
Here are 5 related questions to deepen your understanding:

  1. How do you verify if two vectors are collinear geometrically?
  2. What happens if x12x \neq 12 in this problem? Are the vectors parallel or not?
  3. Can you generalize the collinearity condition to 3D vectors?
  4. How does the direction ratio of the vectors change with different xx?
  5. What are the applications of vector collinearity in physics and engineering?

Tip: Always simplify vector expressions before testing conditions like collinearity—it reduces the chances of error!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Vector Algebra
Collinearity
Linear Equations

Formulas

Collinearity condition: x1 * y2 = x2 * y1
Vector components: AB = B - A, CD = D - C

Theorems

Condition for Collinearity of Two Vectors

Suitable Grade Level

Grades 9-11