Linear Equations - Examples & Applications

This section provides step-by-step examples on how to apply linear equation concepts. You'll learn how to find slopes, write equations in different forms, determine the relationships between lines, and solve applications.

Forms of Linear Equations

Linear equations can be written in Slope-Intercept form (y=mx+by = mx + b), Point-Slope form (yy1=m(xx1)y - y_1 = m(x - x_1)), or Standard form (Ax+By=CAx + By = C). You must know how to convert between them.

Example

Example 1: Slope-Intercept Form to Standard Form (Basic) Convert the equation y=23x+4y = -\frac{2}{3}x + 4 into Standard Form (Ax+By=CAx + By = C, where A,B,A, B, and CC are integers).

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Example

Example 2: Point-Slope to Slope-Intercept Form (Intermediate) Find the equation of the line that passes through the point (4,5)(-4, 5) and has a slope of 12\frac{1}{2}. Write the final equation in Slope-Intercept form.

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Example

Example 3: Standard Form to Slope-Intercept Form (Intermediate) Find the slope and y-intercept of the line given by the equation 5x2y=105x - 2y = 10.

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Distance and Midpoint

Calculating the distance between two points and finding the exact middle point on a coordinate plane.

Example

Example 1: The Distance Formula (Basic) Find the distance between the points (2,3)(2, 3) and (5,7)(5, 7).

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Example

Example 2: The Midpoint Formula (Intermediate) Find the midpoint of the line segment connecting (4,2)(-4, 2) and (6,8)(6, -8).

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Understanding Slope

The slope (mm) of a line measures its steepness and direction. It is defined as the "rise" over the "run" between any two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) on the line: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}.

Example

Example 1: Calculating Slope from Two Points (Basic) Find the slope of the line passing through the points (3,2)(3, -2) and (5,4)(-5, 4).

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Example

Example 2: Finding an Unknown Coordinate (Intermediate) The slope of a line passing through (2,y)(2, y) and (6,11)(6, 11) is 22. Find the value of yy.

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Example

Example 3: Zero and Undefined Slopes (Edge Cases) Find the slopes of the lines passing through: Line A: (4,7)(4, 7) and (2,7)(-2, 7) Line B: (3,1)(3, -1) and (3,5)(3, 5)

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Parallel and Perpendicular Lines

Parallel lines never intersect and have the exact same slope (m1=m2m_1 = m_2). Perpendicular lines intersect at a 90-degree angle and have slopes that are negative reciprocals of each other (m1m2=1m_1 \cdot m_2 = -1).

Example

Example 1: Equation of a Parallel Line (Intermediate) Find the equation of the line that passes through the point (2,4)(-2, 4) and is parallel to the line y=3x5y = 3x - 5. Write the answer in slope-intercept form.

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Example

Example 2: Equation of a Perpendicular Line (Advanced) Find the equation of the line that passes through (6,1)(6, -1) and is perpendicular to the line 2x+3y=122x + 3y = 12. Write the answer in standard form.

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Example

Example 3: Determining the Relationship (Basic) Determine if the following pair of lines are parallel, perpendicular, or neither: Line 1: 4xy=84x - y = 8 Line 2: x+4y=12x + 4y = 12

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