Class 10 Maths - HARYANA

Pair of Linear Equations in Two Variables

The chapter 'Pair of Linear Equations in Two Variables' builds upon algebraic foundations by teaching students how to represent and solve two simultaneous linear equations. Essential for Class 10 Haryana (BSEH) board exams, this chapter introduces graphical methods and algebraic methods including substitution, elimination, and cross-multiplication. Students learn to determine whether systems of equations have unique, infinitely many, or no solutions by comparing coefficient ratios. Mastering this chapter is crucial as it forms the basis for solving complex word problems frequently asked in Board examinations, ensuring a strong grip on both conceptual and application-based questions.

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Key Concepts

Linear Equation in Two Variables

An equation of the form ax + by + c = 0, where a, b, and c are real numbers and a, b are not both zero.

Consistent and Inconsistent Systems

A pair of linear equations is consistent if it has at least one solution (intersecting or coincident lines) and inconsistent if it has no solution (parallel lines).

Graphical Method

A visual way to find solutions where the point of intersection of two lines represents the unique solution of the pair of equations.

Substitution Method

An algebraic technique where the value of one variable from one equation is substituted into the other equation to solve for a single variable.

Elimination Method

An algebraic method of solving pairs of linear equations by multiplying equations to eliminate one variable, making it easier to solve for the other.

Conditions for Solvability

Conditions comparing ratios a1/a2, b1/b2, and c1/c2 to determine if the lines are intersecting, parallel, or coincident.

Important Formulas

General form: a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0
Intersecting lines (Unique solution): a1/a2 != b1/b2
Coincident lines (Infinitely many solutions): a1/a2 = b1/b2 = c1/c2
Parallel lines (No solution): a1/a2 = b1/b2 != c1/c2

Board Exam Info

In the Haryana (BSEH) Class 10 Mathematics board exam, this chapter typically carries around 6 to 8 marks. Common question types include checking consistency of equations, solving a pair of linear equations using the elimination or substitution method, and word problems based on ages, fractions, speed-distance-time, or two-digit numbers.

Frequently Asked Questions

How do I know whether to use the substitution or elimination method in the exam?

You can use any algebraic method unless the question specifically asks for a particular one. Elimination is generally faster and less prone to calculation errors.

What does a 'consistent' pair of linear equations mean graphically?

A consistent pair means the lines either intersect at a single point or overlap completely (coincident lines), meaning they have at least one solution.

Are word problems from this chapter mandatory in the BSEH board exam?

Yes, long-answer questions often feature word problems that require you to first form the pair of linear equations and then solve them.

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