# Variables and Expressions

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Variables are the letters or alphabets usually found in most of the math formulas, in algebraic expressions and equations. Variables can take any number assigned to them as per the given question and therefore we can have the choice to let an alphabet be a certain number. Algebraic expressions are formed when variables and numerical constants are put together joined by addition, subtraction, multiplication or division operations. We can find the value of the expression containing the variables because we can assign the values for the given variable.

Example 1: What is the value of the given algebraic expression, 5a – 8 + 4b if the value of ‘a’ = 1 and b = 2.

In order to find the value of the expression, we should plug-in ‘a’ as ‘1’ and ‘b’ as ‘2’.

This implies: 5a – 8 + 4b = 5(1) – 8+ 4(2)

This gives: 5 – 8 + 8

Now calculate the values starting from the left side of the expression.

5 – 8 + 8 = 5.

Hence the value of the expression is 5.

Example 2:  What is the value of the given algebraic expression, 10 – 7x + 2y if the value of x = 0 and y = -2.

In order to find the value of the expression, we should plug-in x = 0 and y = -2 in the place of ‘x’ and ‘y’.

This implies: 10- 7(0) + 2(-2)

This gives: 10 – 0 - 4

Now calculate the values starting from the left side of the expression.

10- 0 – 4= 6

Hence the value of the expression is 6.