Point Slope Form Calculator
The Point Slope Form Calculator allows you to quickly determine the equation of a line using a known slope and point or using two points. It provides step-by-step solutions and converts the results into different linear equation forms.
- Option 1: Known slope (m) and a point (x₁, y₁)
- Option 2: Two points (x₁, y₁) and (x₂, y₂)
The calculator shows how to form the point-slope equation using y - y₁ = m(x - x₁), then converts it into slope-intercept form (y = mx + b) and standard form (Ax + By = C). It handles integers, decimals, fractions, and vertical lines effectively.
How to Use the Point Slope Form Calculator
Mode A: Using Slope and Point
- Enter the slope m and the point (x₁, y₁).
- Click Calculate.
- Calculator outputs:
- Point-slope equation (step-by-step)
- Slope-intercept form (y = mx + b)
- Standard form (Ax + By = C)
- Graph showing the line passing through the point with slope m
Mode B: Using Two Points
- Enter two points (x₁, y₁) and (x₂, y₂).
- Click Calculate.
- Calculator outputs:
- Slope (m)
- Slope-intercept form (y = mx + b)
- Point-slope form (y - y₁ = m(x - x₁))
- Graph showing both points and the line through them
Understanding Slope
The slope of a line measures its steepness, calculated as the ratio of vertical change (rise) to horizontal change (run) between two points.
- Positive slope → line rises left to right
- Negative slope → line falls left to right
- Zero slope → horizontal line
- Undefined slope → vertical line
Point-Slope Form Derivation
Starting from the slope formula:
m = (y - y₁) / (x - x₁)
Where:
- m = slope
- (x₁, y₁) = known point
- (x, y) = any point on the line
Multiply both sides by (x - x₁):
y - y₁ = m(x - x₁)
This is the point-slope form of a line.
Finding the Equation of a Line
1️⃣ Using Slope and a Point
- Identify the slope m and point (x₁, y₁).
- Substitute into y - y₁ = m(x - x₁).
- Simplify to slope-intercept or standard form.
Example: Slope m = 3, point (2, 5)
y - 5 = 3(x - 2)
y - 5 = 3x - 6 → y = 3x - 1
2️⃣ Using Two Points
- Calculate slope: m = (y₂ - y₁)/(x₂ - x₁).
- Substitute slope and one point into y - y₁ = m(x - x₁).
- Simplify to slope-intercept or standard form.
Example: Points (0,1) and (4,5)
Slope: m = (5 - 1)/(4 - 0) = 1
Point-slope: y - 1 = 1(x - 0)
Simplify: y - 1 = x → y = x + 1
Interpretation:
- Positive slope → line rises
- Negative slope → line falls
- Vertical line: slope undefined, x = constant
- Horizontal line: slope 0, y = constant
Converting Point-Slope to Slope-Intercept Form
- Start with y - y₁ = m(x - x₁)
- Distribute: y - y₁ = mx - mx₁
- Add y₁: y = mx - mx₁ + y₁
- Simplify: y = mx + (y₁ - mx₁)
FAQs
What are the different forms of linear equations?
- Standard Form: Ax + By = C
- Point-Slope Form: y - y₁ = m(x - x₁)
- Slope-Intercept Form: y = mx + b
What is the equation of a straight line?
The equation describes all points on a line:
y = mx + b
- m = slope
- b = y-intercept
References
- Khan Academy: Introduction to Point-Slope Form
- StudyPug: Linear Equations Using Point-Slope Form