Math Problem Statement

Which equation in slope-intercept represents the line that goes through the points (-1, -5) and (1, -1)?

Solution

The problem asks for the slope-intercept equation of the line that passes through the points (-1, -5) and (1, -1). Let's calculate step-by-step:

1. Find the slope (m):

The slope mm is calculated as: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} Substituting (x1,y1)=(1,5)(x_1, y_1) = (-1, -5) and (x2,y2)=(1,1)(x_2, y_2) = (1, -1): m=1(5)1(1)=1+51+1=42=2m = \frac{-1 - (-5)}{1 - (-1)} = \frac{-1 + 5}{1 + 1} = \frac{4}{2} = 2

2. Write the equation in slope-intercept form:

The slope-intercept form of a line is: y=mx+by = mx + b We now know m=2m = 2, so the equation becomes: y=2x+by = 2x + b

3. Find the y-intercept (bb):

Substitute one of the given points, say (1,5)(-1, -5), into the equation y=2x+by = 2x + b: 5=2(1)+b-5 = 2(-1) + b 5=2+b-5 = -2 + b b=5+2=3b = -5 + 2 = -3

4. Final equation:

The equation of the line is: y=2x3y = 2x - 3

Correct answer:

The correct choice is: y=2x3\boxed{y = 2x - 3}

Would you like a detailed explanation of any step?
Here are 5 related questions to expand your understanding:

  1. How do you derive the slope formula for a straight line?
  2. What is the importance of slope-intercept form in graphing?
  3. How do you determine if two points lie on the same line?
  4. Can you explain why substituting a point into the equation gives the y-intercept?
  5. What is the geometric significance of the slope and y-intercept?

Tip: Always verify your equation by substituting both points to check if they satisfy the equation.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form
Coordinate Geometry

Formulas

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

Theorems

Equation of a line passing through two points

Suitable Grade Level

Grades 8-10