Math Problem Statement

Determine if the lines 6y = x - 12 and 18y + 36 = 3x are parallel, perpendicular, or neither. Justify your answer.

Solution

Let's examine the two equations provided and determine if the lines are parallel, perpendicular, or neither.

Step 1: Convert both equations to slope-intercept form y=mx+by = mx + b, where mm is the slope.

  1. First equation: 6y=x126y = x - 12 Divide both sides by 6 to solve for yy: y=16x2y = \frac{1}{6}x - 2 So, the slope m1m_1 of the first line is 16\frac{1}{6}.

  2. Second equation: 18y+36=3x18y + 36 = 3x Subtract 36 from both sides: 18y=3x3618y = 3x - 36 Divide both sides by 18 to solve for yy: y=16x2y = \frac{1}{6}x - 2 So, the slope m2m_2 of the second line is also 16\frac{1}{6}.

Step 2: Compare the slopes

  • If the slopes are equal and the intercepts differ, the lines are parallel.
  • If the slopes are negative reciprocals of each other (i.e., m1×m2=1m_1 \times m_2 = -1), the lines are perpendicular.
  • If neither of the above conditions is met, the lines are neither parallel nor perpendicular.

Here, both lines have the same slope 16\frac{1}{6} and the same y-intercept (-2). Therefore, the lines are identical (coincident), meaning they are parallel and overlap completely.

Final Answer: The lines are parallel.


Do you need more details on this, or have any questions?

Here are five related questions to expand on this concept:

  1. How do we determine if two lines are perpendicular in three dimensions?
  2. What happens if two lines have the same slope but different intercepts?
  3. How would you write the equation of a line perpendicular to one of these lines?
  4. Can lines with undefined slopes (vertical lines) be parallel?
  5. What is the geometric interpretation of coincident lines?

Tip: To easily find if two lines are perpendicular, just check if the product of their slopes equals -1!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slopes of Lines

Formulas

Slope-Intercept Form (y = mx + b)
Parallel Lines (equal slopes)
Perpendicular Lines (negative reciprocal slopes)

Theorems

Slope-Intercept Theorem

Suitable Grade Level

Grades 9-10