Math Problem Statement

Find an equation for the line that passes through the points -4,-5 and 2,-1

Solution

To find the equation of the line that passes through the points (4,5)(-4, -5) and (2,1)(2, -1), we can use the slope-intercept form of a line equation:

y=mx+by = mx + b

where mm is the slope and bb is the y-intercept.

Step 1: Find the Slope (mm)

The formula for the slope between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is:

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

Using the points (4,5)(-4, -5) and (2,1)(2, -1):

m=1(5)2(4)=1+52+4=46=23m = \frac{-1 - (-5)}{2 - (-4)} = \frac{-1 + 5}{2 + 4} = \frac{4}{6} = \frac{2}{3}

So, the slope mm is 23\frac{2}{3}.

Step 2: Substitute into the Point-Slope Form

Now that we have the slope, we can use the point-slope form of the line equation to find the equation. The point-slope form is:

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

Using the point (2,1)(2, -1) and m=23m = \frac{2}{3}:

y(1)=23(x2)y - (-1) = \frac{2}{3}(x - 2)

Simplify this equation:

y+1=23x43y + 1 = \frac{2}{3}x - \frac{4}{3}

Now, subtract 1 from both sides to isolate yy:

y=23x4333y = \frac{2}{3}x - \frac{4}{3} - \frac{3}{3}

y=23x73y = \frac{2}{3}x - \frac{7}{3}

Final Answer

The equation of the line is:

y=23x73y = \frac{2}{3}x - \frac{7}{3}

Would you like further details or have any questions?


  1. How do you determine the y-intercept of a line?
  2. Can you explain how to convert between different forms of a line equation?
  3. What is the significance of the slope in a line equation?
  4. How can you verify if a point lies on a given line?
  5. How would the equation change if one of the points were different?

Tip: Always double-check your slope calculation, as a small mistake can lead to an incorrect line equation.

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Math Problem Analysis

Mathematical Concepts

Algebra
Coordinate Geometry
Linear Equations

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