Math Problem Statement

What is an equation of the line that passes through the points left parenthesis, 2, comma, minus, 5, right parenthesis(2,−5) and left parenthesis, minus, 8, comma, 5, right parenthesis(−8,5)?

Solution

To find the equation of a line passing through two points, (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2), we can use the point-slope form of the line equation. Here's the process:

Step 1: Find the slope of the line

The slope mm of a line passing through two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is given by the formula:

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

Substituting the given points (2,5)(2, -5) and (8,5)(-8, 5):

m=5(5)82=5+582=1010=1m = \frac{5 - (-5)}{-8 - 2} = \frac{5 + 5}{-8 - 2} = \frac{10}{-10} = -1

Step 2: Use the point-slope form

The point-slope form of the equation of a line is:

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

We can use either of the points. Let's use the point (2,5)(2, -5):

y(5)=1(x2)y - (-5) = -1(x - 2)

Simplifying:

y+5=1(x2)y + 5 = -1(x - 2)

Distribute the 1-1:

y+5=x+2y + 5 = -x + 2

Subtract 5 from both sides:

y=x+25y = -x + 2 - 5

y=x3y = -x - 3

Final equation:

The equation of the line is:

y=x3y = -x - 3

Would you like more details or have any questions?

Here are 5 related questions to deepen understanding:

  1. What would be the equation if the points were different?
  2. How do you find the equation of a vertical line?
  3. How can you write the equation in standard form?
  4. How does the slope of a line affect its graph?
  5. How can you verify that the equation is correct by substituting the points?

Tip: To quickly identify the slope between two points, remember that a positive slope rises, and a negative slope falls.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form
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

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Suitable Grade Level

Grades 8-10