Some shopping malls use high-frequency “mosquito sounds” to stop teenagers from gathering in certain areas. It may sound strange, but the reason behind it is mostly economic. Malls want their space to be occupied by people who will likely spend money. When large groups of teenagers hang around without buying anything, they take up space, create noise, and make the area feel more crowded. This can discourage adult consumers, who usually spend more, from staying longer in the stores. In economics, every part of a mall is considered valuable. The goal is to increase revenue from each square metre. If a space is filled with people who are not contributing to sales, the mall sees that as an inefficient use of resources. Instead of hiring more staff or redesigning the whole area, playing mosquito-frequency sounds is a low-cost method to change customer behaviour. While this method may feel controversial, it shows how businesses use simple tools to manage customer flow and maximise economic efficiency.

Differentiation is the process of measuring how fast a function changes. Some of the readers may have learned it in IGCSE Year 2 Maths. This paragraph will explain deeper about how mathematicians developed the idea behind this concept. On the curve above, point A represents the value of f(x) at x, and point B represents the value of f(x+h) at point (x+h). The straight line (the yellow line) connecting two points A and B is called a secant line. The slope of this line can be calculated by the formula: Gradient = rise/run: ⇒ f(x+h) - f(x)/(x+h)-x ⇒ f(x+h) - f(x)/h This secant line represents the average rate of change between the two points A and B. As h becomes smaller (approaches zero), it means that point B gets closer to point A, and the secant line becomes a tangent line. This process gives the exact slope of a curve at a point, which is called the derivative.

Helo mng mình là Khánh Hà (Khà), mình sẽ làm mentor Maths IG năm nay, rất mong rằng dự án của NSSC sẽ đạt được nhiều thành công!!!