CBSE Class 7th Maths

Simple Equations

Simple Equations

Equations involving only a linear polynomial are called simple equations.
e.g. 4x + 5 = 65, 10y – 20 = 50

In an equation, there is always an equality sign.

A Simple Equation remains the same when the expression in the left and right are interchanged.

The value of a variable, which makes the equation a true statement is called the solution of a linear equation.
e.g. 5x – 12 = -2 is a equation
L.H.S = 5x – 12 = 5 × 2 – 12 = 10 – 12 = -2
L.H.S = R.H.S

Variables and Expressions

Variable is a quantity that can take any value, its value is not fixed. It is a symbol for a number whose value is unknown yet.

Expressions are formed by performing operations like addition, subtraction, multiplication and division on the variables.

Example: 6x – 3 is an expression in variable x.

Algebraic Equation

An equation is a condition on a variable such that two expressions in the variable should have equal value.

Example: 8x8=16 is an equation.

The value of the variable in an equation for which the equation is satisfied is called the solution of the equation.​

​​​​​​Example: The solution for the equation 2x3=5 is x=4.

Mathematical Operations on Expressions

  • Addition of variables: (3x+4z)+(5y+6)
  • Subtraction of variables: (4x7y)(6y+5)
  • Multiplication of variables: (5xy+6)×7x
  • Division of variables: (8xz+5z)/(5x-6y)
NCERT Solutions


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