Rate of Change from Equation Calculator

Rate of Change from Equation Calculator

Calculate the instantaneous or constant rate of change for any linear or power function

Linear Equation (y = mx + b) Power Function (f(x) = axⁿ + c)
Rate of Change

Understanding Rate of Change

The rate of change describes how one quantity changes in relation to another. In mathematical terms, for a function y = f(x), it represents the change in y divided by the change in x. This is also commonly known as the slope of the function.

Constant vs. Instantaneous Rate of Change

Depending on the type of equation, the rate of change can be fixed or variable:

  • Linear Equations: The rate of change is constant. In the form y = mx + b, the rate of change is always equal to m.
  • Non-Linear Equations: For curves (like quadratics or power functions), the rate of change varies at different points. This is called the instantaneous rate of change and is found using the derivative of the function.

The Formulas Used

For a power function f(x) = axⁿ, the instantaneous rate of change at point x is calculated using the power rule for derivatives:

f'(x) = n · a · x(n-1)

Real-World Example

If an object's position is defined by the equation d = 5t² (where d is distance and t is time), the rate of change represents the velocity. To find the velocity at t = 3 seconds:

  1. Identify a = 5, n = 2, and x = 3.
  2. Apply the power rule: 2 · 5 · 3(2-1).
  3. Calculation: 10 · 3 = 30 units/second.
function toggleInputs() { var type = document.getElementById("equationType").value; var linearDiv = document.getElementById("linearInputs"); var powerDiv = document.getElementById("powerInputs"); if (type === "linear") { linearDiv.style.display = "block"; powerDiv.style.display = "none"; } else { linearDiv.style.display = "none"; powerDiv.style.display = "block"; } document.getElementById("resultArea").style.display = "none"; } function calculateRateOfChange() { var type = document.getElementById("equationType").value; var resultArea = document.getElementById("resultArea"); var resultValue = document.getElementById("resultValue"); var resultFormula = document.getElementById("resultFormula"); var rate = 0; var formulaText = ""; if (type === "linear") { var m = parseFloat(document.getElementById("coeffM").value); var b = parseFloat(document.getElementById("constB").value); if (isNaN(m) || isNaN(b)) { alert("Please enter valid numbers for the linear equation."); return; } rate = m; formulaText = "For y = " + m + "x + " + b + ", the rate of change is constant (slope m)."; } else { var a = parseFloat(document.getElementById("coeffA").value); var n = parseFloat(document.getElementById("exponentN").value); var x = parseFloat(document.getElementById("pointX").value); if (isNaN(a) || isNaN(n) || isNaN(x)) { alert("Please enter valid numbers for the power function."); return; } // Power Rule: f'(x) = n * a * x^(n-1) if (n === 0) { rate = 0; } else { rate = n * a * Math.pow(x, n – 1); } formulaText = "Derivative f'(x) = (" + n + " · " + a + ") · " + x + "(" + n + "-1)"; } resultValue.innerHTML = Number.isInteger(rate) ? rate : rate.toFixed(4); resultFormula.innerHTML = formulaText; resultArea.style.display = "block"; }

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