Math Problem Statement

how do u find the equation of a line given two points

Solution

To find the equation of a line given two points, you follow these steps:

1. Use the two points to find the slope (m):

If the points are (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2), the slope of the line is given by the formula:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

2. Use the point-slope form of the equation:

The equation of a line can be written in point-slope form:

yy1=m(xx1)y - y_1 = m(x - x_1)

Here, mm is the slope (calculated in Step 1) and (x1,y1)(x_1, y_1) is one of the given points.

3. Simplify to the slope-intercept form (if needed):

To express the equation in slope-intercept form (y=mx+by = mx + b), solve for yy and simplify. If necessary, substitute one of the points into the equation to find the y-intercept (bb).


Example:

Find the equation of the line passing through the points (2,3)(2, 3) and (4,7)(4, 7).

  1. Calculate the slope: m=y2y1x2x1=7342=42=2m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{7 - 3}{4 - 2} = \frac{4}{2} = 2

  2. Write the point-slope form: Using point (2,3)(2, 3), y3=2(x2)y - 3 = 2(x - 2)

  3. Simplify to slope-intercept form: Expand and simplify: y3=2x4    y=2x1y - 3 = 2x - 4 \implies y = 2x - 1

Thus, the equation of the line is: y=2x1y = 2x - 1


Do you want me to demonstrate with a specific example or clarify any step?

Related Questions:

  1. How do you find the equation of a vertical line given two points?
  2. What is the general form of a linear equation, and how does it relate to point-slope form?
  3. How can you verify that a point lies on a given line?
  4. What is the equation of a line parallel to another line passing through a specific point?
  5. How do you find the midpoint of the line segment between two points?

Tip:

Always check the coordinates carefully when calculating the slope to avoid sign errors!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope of a Line
Point-Slope Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Point-slope form: y - y1 = m(x - x1)
Slope-intercept form: y = mx + b

Theorems

Basic properties of linear equations

Suitable Grade Level

Grades 8-10