Calculate Line Equation

Online calculator and formulas for calculating the linear line equation

Line Equation Calculator

Linear Function

The line equation f(x) = m·x + n describes a line through slope m and y-intercept n.

What should be calculated?
Result of the linear function
Slope of the line
X-coordinate (input value)
Intersection with Y-axis
Results
Function f(x):
Slope m:
Argument x:
Y-intercept n:

Visualization

Line equation

The graphic shows a linear function f(x) = m·x + n.
The slope m determines the inclination, n the y-intercept.

What is a Line Equation?

A line equation describes a straight line in a coordinate system:

  • Definition: f(x) = m·x + n (standard form)
  • Slope m: How steep the line runs
  • Y-intercept n: Where the line intersects the Y-axis
  • Application: Description of linear relationships
  • Calculation: Determine any parameter
  • Graph: Unique representation of a line

How Does the Calculator Work?

The calculator solves the line equation for the selected parameter:

Calculate Function
\[f(x) = m \cdot x + n\]

Given slope m, X-value and y-intercept n

Calculate Slope
\[m = \frac{f(x) - n}{x}\]

Given function, X-value and y-intercept

Formulas for Line Equation

Basic Form of Line Equation
\[f(x) = m \cdot x + n\]

Standard form of a linear function

Calculate Slope
\[m = \frac{f(x) - n}{x}\]

Slope from function, X-value and y-intercept

Calculate X-value
\[x = \frac{f(x) - n}{m}\]

X-coordinate from function, slope and y-intercept

Calculate Y-intercept
\[n = f(x) - m \cdot x\]

Y-intercept from function, slope and X-value

Example

Given
m = 4 x = 5 n = 6
Calculation of f(x)
\[f(x) = 4 \cdot 5 + 6\] \[f(x) = 20 + 6 = 26\]

The function value is 26

Meaning
  • Slope 4: Y increases by 4 per X-unit
  • Y-intercept 6: Line intersects Y-axis at 6
  • Point (5,26): Lies on the line
Applications

Economics (cost-revenue), physics (uniform motion), statistics (regression).

Understanding Linear Functions

A line equation is a mathematical description of a straight line in a two-dimensional coordinate system. It is the simplest form of a function and describes a linear relationship between two variables.

The Standard Form: f(x) = m·x + n

In the standard form of a linear function, the parameters have the following meaning:

  • m (slope): Indicates how many units the Y-value rises or falls when the X-value increases by 1
  • n (y-intercept): Indicates the Y-value at which the line intersects the Y-axis (i.e., at x = 0)
  • x (variable): The independent variable (input value)
  • f(x) (function value): The dependent variable (output value)

Properties of Linear Functions

Positive Slope (m > 0)

The line rises from left to right. The larger m, the steeper the rise.

Negative Slope (m < 0)

The line falls from left to right. The smaller m, the steeper the fall.

Zero Slope (m = 0)

The line runs horizontally. The function value is constant: f(x) = n.

Y-intercept

The point (0, n) always lies on the line, regardless of the slope.

Practical Applications

Linear functions are found in many areas of daily life:

  • Economics: Cost-revenue functions, depreciation
  • Physics: Uniform motion, Ohm's law
  • Everyday mathematics: Mobile phone tariffs, rent costs, fuel consumption
  • Statistics: Linear regression, trend analysis

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