Class 10 Maths - KARNATAKA

Pair of Linear Equations in Two Variables

The chapter 'Pair of Linear Equations in Two Variables' builds on your understanding of single-variable linear equations by introducing two related equations with two unknowns, usually represented as x and y. You will learn to find their solutions using graphical methods and algebraic methods such as substitution, elimination, and cross-multiplication. For SSLC board exams, this is a high-scoring chapter that tests your problem-solving and word-problem translation skills. Understanding how to determine if lines are intersecting, parallel, or coincident is crucial for scoring top marks.

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Key Concepts

General Form of a Pair of Linear Equations

Represented as a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0, where a1, b1, a2, b2, c1, and c2 are real numbers and a1^2 + b1^2 ≠ 0 and a2^2 + b2^2 ≠ 0.

Consistent and Inconsistent Systems

A system of equations with at least one solution is called consistent, while a system with no solution is called inconsistent.

Graphical Method

Plotting the lines on a graph; intersecting lines mean a unique solution, parallel lines mean no solution, and coincident lines mean infinitely many solutions.

Algebraic Methods of Solution

Techniques including the Substitution Method and the Elimination Method used to find exact numerical values for the variables without drawing graphs.

Condition for Solvability

Using ratio comparisons (a1/a2, b1/b2, c1/c2) to predict the nature of solutions before actually solving the equations.

Important Formulas

a1/a2 ≠ b1/b2 (Unique solution, intersecting lines)
a1/a2 = b1/b2 ≠ c1/c2 (No solution, parallel lines)
a1/a2 = b1/b2 = c1/c2 (Infinitely many solutions, coincident lines)

Board Exam Info

In the Karnataka SSLC (KSEEB) Mathematics exam, this chapter typically carries around 6 to 8 marks. Expect 1-mark objective questions, 2-mark graphical or consistency check questions, and a 3 or 4-mark word problem based on ages, fractions, or speed-distance.

Frequently Asked Questions

How do I know whether to use substitution or elimination?

Elimination is generally faster and easier when coefficients are simple numbers or already match. Substitution is preferred when one variable already has a coefficient of 1 or -1.

Are graph sheets provided for the exam?

Yes, graph sheets are provided in the main answer booklet or separately by the invigilator when a graphical question is asked in the SSLC exam.

How many solutions does a dependent pair of linear equations have?

A dependent pair of linear equations has infinitely many solutions because the two equations represent the exact same line.

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