Math Problem Statement

Write the equation of a line that passes through the point (− 6, 9) and is perpendicular to a line that passes through the points (− 2, 1) and (6, 7) in slope-intercept form.

Solution

To write the equation of a line that passes through the point (6,9)(-6, 9) and is perpendicular to a line that passes through the points (2,1)(-2, 1) and (6,7)(6, 7), we can follow these steps:

Step 1: Find the slope of the line passing through points (2,1)(-2, 1) and (6,7)(6, 7)

The slope m1m_1 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:

m1=y2y1x2x1m_1 = \frac{y_2 - y_1}{x_2 - x_1}

Substituting the given points (2,1)(-2, 1) and (6,7)(6, 7):

m1=716(2)=66+2=68=34m_1 = \frac{7 - 1}{6 - (-2)} = \frac{6}{6 + 2} = \frac{6}{8} = \frac{3}{4}

Step 2: Find the slope of the perpendicular line

The slope of the line perpendicular to the one found above will be the negative reciprocal of m1m_1. If the slope of one line is m1m_1, the slope of the perpendicular line m2m_2 is:

m2=1m1=134=43m_2 = -\frac{1}{m_1} = -\frac{1}{\frac{3}{4}} = -\frac{4}{3}

Step 3: Write the equation of the perpendicular line

Now we know the slope m2=43m_2 = -\frac{4}{3} and the line passes through the point (6,9)(-6, 9). The equation of a line in slope-intercept form is given by:

y=mx+by = mx + b

We can substitute the slope m=43m = -\frac{4}{3} and the point (6,9)(-6, 9) into this equation to solve for bb, the y-intercept.

Substitute x=6x = -6, y=9y = 9, and m=43m = -\frac{4}{3}:

9=43(6)+b9 = -\frac{4}{3}(-6) + b

Simplify:

9=8+b9 = 8 + b

Solving for bb:

b=98=1b = 9 - 8 = 1

Step 4: Final equation

The equation of the line is:

y=43x+1y = -\frac{4}{3}x + 1

This is the equation of the line in slope-intercept form that passes through the point (6,9)(-6, 9) and is perpendicular to the line passing through the points (2,1)(-2, 1) and (6,7)(6, 7).

Do you need any further explanation or details?


Here are 5 related questions to deepen your understanding:

  1. How do you find the equation of a line that is parallel to a given line?
  2. What is the geometric interpretation of a negative slope?
  3. Can a vertical line be perpendicular to a horizontal line? Why?
  4. How do you find the midpoint between two points on a line?
  5. What is the significance of the slope-intercept form of a line in graphing?

Tip:

When solving for the slope of a line, always be careful with the signs when subtracting coordinates to avoid common errors.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form
Perpendicular Lines

Formulas

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

Theorems

Perpendicular slopes have negative reciprocal relationships

Suitable Grade Level

Grades 8-10