APPLICATIONS OF CALCULUS
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Subject: Additional Mathematics
Class: SHS 1
Term: 2nd Term
Week: 13
Grade code: 1.3.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.1
Indicator code: 1.3.2.LI.2
Theme: CALCULUS
Subtheme: APPLICATIONS OF CALCULUS
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This lesson introduces one of the most powerful applications of calculus: understanding and calculating rates of change. We often talk about how fast things change in our daily lives – the speed of a car, the rate at which prices increase, or how quickly a disease spreads. While we can easily calculate an *average* speed over a journey, calculus allows us to find the *exact* speed at a single moment in time. This concept, known as the instantaneous rate of change, has wide applications in science, engineering, economics, and even public health in Ghana, from analysing the performance of our Black Stars to managing our national economy.
Part 1: Revisiting the Average Rate of Change
You already know how to find the gradient (slope) of a straight line connecting two points, `(x₁, y₁)` and `(x₂, y₂)`:
``` Gradient (m) = (Change in y) / (Change in x) = (y₂ - y₁) / (x₂ - x₁) = Δy / Δx ```
This gradient represents the average rate of change of `y` with respect to `x`. For a curve, this formula gives the gradient of the *secant line* connecting two points on the curve.