Pair of Linear Equations in Two Variables Class 10 Notes Chapter 3:

Equation: Assertion that two mathematical expressions with one or more variables are equal is called an equation

Equation of a Line: Linear equations are those in which the powers of all the variables involved are equal. A linear equation's degree is always one.

A Linear Equation in Two Variables in Its General Form

A linear equation in two variables has the generic form ax + by + c = 0, where a and b cannot be zero at the same time.

Students can use the short notes and MCQ questions, as well as the standalone notes.

For easy revision, get the solution pdf for this chapter from the links below:

• Pair of linear Equations in Two Variables- Notes
• Pair of linear Equations in Two Variables-MCQ Questions for Practice
• Pair of linear Equations in Two Variables-Solutions for MCQ Practice

For a word problem, representing linear equations: Using a linear equation to illustrate a word problem

• Identify unknown quantities and assign variables to them.
• Replacing the unknowns with variables, represent the relationships between quantities in a mathematical

CBSE Class 10 Maths Chapter 3 Pair of Linear Equations in Two Variables Notes- Free PDF Download

Solution of Linear Equation in two variables:

A pair of numbers, one for x and the other for y, that make the two sides of the equation equal is the solution of a linear equation in two variables.

Solution in Graphics

Graphically representing a pair of linear equations in two variables:

A pair of straight lines can be used to depict a pair of linear equations in two variables graphically.

The following is a graphical method for determining the solution to a pair of linear equations:

• Plot the two equations together (two straight lines)
• Find the location where the lines intersect.
• The solution is the point of intersection.

Algebraic Solution

Finding a solution to a pair of Linear Equations that are consistent.

The solution of a pair of linear equations is in the form (x,y), which simultaneously solves both equations. It is possible to get a solution for a consistent pair of linear equations by using

• Method of elimination
• Method of Substitution
• Method of cross-multiplication
• Graphical approach

Finding a solution to a pair of linear equations using the substitution method:

Method of substitution:

y – 4x = 1

x + 4y= 38

1. Using one of the equations, express one variable in terms of the other. Y = 4x + 1 in this situation.
2. Substitute this variable (y) in the second equation to obtain a one-variable linear equation,

x + 4 (4x + 1) = 38

x + 16x + 4 = 38

17x + 4 = 38

17x = 38-4

17x= 34

X= 2

17 multiplied by 2 equals 34

To find the value of a variable, solve the linear equation in that variable.

X = 2

1. Substitute this value for the other variable’s value in one of the equations.

Y = 4x + 1

Y = 8 + 1

Y = 9

As a result, the solution to the set of linear equations y – 4x = 1 and x + 4y = 38 is (2,9).

Finding a solution to a pair of linear equations using the elimination approach

Method of elimination

Consider the expressions x + 4y = 10 and 2x – y = 2.

Step 1: By multiplying the coefficients of any variable, you can make them the same.

By multiplying the equations with constants, you can achieve the same result. When we divide the first equation by two, we get

20 = 2x + 8y

Step 2: To eliminate one variable, add or subtract the equations, resulting in a single variable equation.

Subtract the second equation from the first.

20 = 2x + 8y

2x – y = 2 – + – ——————– 0(x) + 9y = 18

Step 3: Solve for one variable and use the result to solve for the other variable in any equation.

Y = 2

X = 10 – 4y

X= 10 – 4*2= 10 – 8

X = 2

Cross-multiplication A method for solving a pair of linear equations.

In the case of the pair of linear equations

a1+ b1+ c1=0

a2x + b2y + c2=0,
x and y can be calculated as

x = (b1c2−b2c1)/(a1b2−a2b1)

y = (c1a2−c2a1)/(a1b2−a2b1

Using Linear Equations to Solve Problems:

Equations that can be reduced to a pair

Questions in two variables that can be reduced to a pair of Linear Equations.

Some equations can be simplified to a linear equation by substituting one variable for another.

2/x+3/y=4

5/x−4/y=9

In this situation, we can make the change.

1/x is equal to u, and 1/y is equal to v.

2u + 3v = 4 5u – 4v = 9 is the result of the pair of equations.

It is possible to solve the above pair of equations. Back replace the values of x and y after you’ve solved the problem.