ප්‍රස්තාර — සා/පෙළ ගණිතය

A graph is a visual representation of the relationship between two variables. In Grade 11, we focus on graphs of linear functions (straight lines) and quadratic functions (parabolas). Understanding graphs involves interpreting key features such as intercepts, gradient, turning points, and symmetry.

Coordinate System: We use the Cartesian plane, defined by a horizontal x-axis and a vertical y-axis. Every point is represented by an ordered pair (x, y). The point where the axes intersect is the origin (0, 0).

Linear Graphs: A linear graph is a straight line. It represents a relationship of the form y = mx + c, where: m is the gradient (slope) of the line. It measures steepness and direction. A positive m means the line slopes upward to the right; a negative m means it slopes downward to the right. m = (change in y) / (change in x) = (y2 - y1) / (x2 - x1). c is the y-intercept, the point where the line crosses the y-axis (at x = 0).