# Definition of Expression in Math

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We can define expression is a combination of numbers and variable with mathematical operations. We can treat the variable as a letter, but it represents a number. For example, 3x + 4 is an expression. With the variable x, this is the linear expression. We can call this ax^2 + bx + c as quadratic expression in terms of variable x.

Problem 1: Simplify the expression 7 (x – 4) + 3 (4 – x).

Solution: Step1: The given expression is = 7 (x – 4) + 3 (4 – x)

=> Step2: We can write this as = 7x – 28 + 12 – 3x

= (7x – 3x)+ (12 – 28)

=> Step3: We can write the above expression as in decreasing powers of x.

=> That is 4x – 16.

Problem 2: Simplify the expression (x – 2) ^2 + (3 – 2x) ^2.

Solution: Step1: The given expression is = (x – 2) ^ 2 + (3- 2x) ^2

=> Step2: To simplify this we can use the formula (a – b) ^2 = a ^2 + b ^2 – 2 a b

=> Step3: We can write the above expression as = x ^2 + 4 – 4x + 9 + 4 x^2 – 12 x

=> Step 4: we can write this as = 5 x^2 – 16 x + 13.