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# CBSE Class 7 Maths Notes for Chapter 4 Simple Equations

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CHAPTER 4 SIMPLE EQUATIONS

VARIABLE

A variable can take any numerical value.

EQUATION

An equation is an expression on the Left Hand Side (L.H.S) being equal to the expression on the Right Hand Side (R.H.S).
For example:      2x + 9 = 9x -5 is an equation.

SOLVING AN EQUATION

In order to solve an equation, we need to make sure that it is balanced.

In case of the balanced equation, if we
(i) add the same number to both the sides, or
(ii) subtract the same number from both the sides, or
(iii) multiply both sides by the same number, or
(iv) divide both sides by the same number,

the balance remains undisturbed, i.e., the value of the L.H.S. remains equal to the value of the R.H.S.

We can perform balanced operations on an equation to solve it.

We can also transpose i.e. move a part to the other side. Transposing a number means changing its sign.

For e.g.  2x + 9 = 4x + 5. Moving 9x from RHS to the LHS and moving 9 from the LHS to the RHS, we get 2x – 4x = 5 – 9 which simplifies to  -2x = -4 which gives x = 2.