# What Have We Discussed?

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- An
equation is **an equality involving variables**. It says that the value of the expression on one side of the equality sign is equal to the value of the expression on the other side.

2. The equations we have studied in this chapter are linear equations in

3. In such equations, **the expressions which form the equation contain only one variable**. Further, the equations are linear, i.e., the highest power of the variable appearing in the equation is

4. **An equation may have linear expressions on both sides**. Equations that we studied in earlier classes had just a

5. Just as numbers, variables can also, be transposed from

6. Occasionally, **the expressions forming equations have to be simplified before we can solve them** by usual methods. Some equations may not even be linear to begin with, but they can be brought to a linear form by

7. The utility of linear equations is in their diverse applications; different problems on numbers, ages, perimeters, combination of currency notes, and so on can be solved using linear equations.