Linear Equations in Two Variables
One equation in two unknowns has not one answer but a whole line of them. Chapter 4, Linear Equations in Two Variables, of the NCERT Mathematics textbook for Class 9 explores equations of this form and their graphs. You will find many solutions by substitution, verify that the graph is always a straight line, study lines parallel to the axes, and model word problems from fares, temperatures and mixtures. Each problem ends by checking that the chosen point truly lies on the line.
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