1. Numerical Expressions
Digital Lesson
Numerical Expressions

2. Examples of Numerical Expressions
These are examples of numerical expressions.
grouping symbols
A numerical expression is an expression formed from numbers by adding, subtracting, multiplying, dividing, taking powers, taking roots, and using grouping symbols: ( ), [ ], | |, { }, and the horizontal bar as in fractions and radicals.
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Examples of Numerical Expressions

3. Example: Evaluate the Numerical Expression
To evaluate a numerical expression, carry out the indicated operations to arrive at a single numerical value.
Examples: Evaluate.
1. 8 – 5(2) + 1
= 8 –
= – 2 + 1
= – 1
Value
2. – 2 + 3(7)
= –
= 19
Value 3.
– 1 + 5
= 7 – 1 + 5
= 6 + 5
= 11
Value
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Example: Evaluate the Numerical Expression

4. Example: Evaluate the Variable Expression
To evaluate a variable expression at a given value, substitute the variable with its value, then evaluate the numerical expression.
Examples: 1. Evaluate 2x + 3 when x = 5.
2(5) + 3
= 13
Value
2. Evaluate 3x2 + x – 4 when x = 2.
3(2)2 + (2) – 4
= 3 • 4 + (2) – 4
= 10
Value
3. Evaluate when x = 3 and y = 1.
(3) (1)
(1) 1 1
Value
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Example: Evaluate the Variable Expression

5. Addition and Subtraction of Signed Numbers
Adding and Subtracting Signed Numbers
Examples: Add or subtract.
1. – 1 + (– 3)
= – 4
The signs are the same, so add the absolute values and attach the common sign. 1 2 3 4 -4 -3 -2 -1
2. – 4 + 6
= 2
The signs are different, so subtract the absolute values and attach the sign of the number with the larger absolute value. 1 2 3 4 -4 -3 -2 -1
3. – 2 – (– 3)
= – 2 + 3
= 1
To subtract, write the expression as the addition of the opposite number. 1 2 3 4 -4 -3 -2 -1
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Addition and Subtraction of Signed Numbers

6. Multiplication and Division of Signed Numbers
Multiplying and Dividing Signed Numbers
Examples: Multiply or divide.
1. (– 6) · (– 2)
= 12
The signs are the same, so the product is positive.
2. (– 5) · 4
= – 20
The signs are different, so the product is negative.
Every division can be written as a multiplication problem. 3.
The signs are different, so the quotient is negative. 4.
= 3
The signs are the same, so the quotient is positive.
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Multiplication and Division of Signed Numbers

7. Examples: 1. Evaluate – x + 2x when x = – 5.
The arithmetic of signed numbers and fractions can be used to evaluate numerical expressions.
Examples: 1. Evaluate – x + 2x when x = – 5.
Signs are the same, so the product will be positive.
– (– 5) + 2(– 5)
= –1 · (– 5) + 2 · (– 5)
= · (– 5)
Signs are different, so the product will be negative.
= 5 + (– 10)
Signs are different. Subtract.
= – 5
2. Evaluate when x = – 2.
(– 2)
Division by zero is undefined.
This expression is undefined when x = – 2.
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Examples: Evaluate

8. Adding and Subtracting Fractions
Examples: Add or subtract.
The denominators are the same, so add the numerators. 1.
Place the sum over the common denominator. 2.
The denominators are the same, so subtract the numerators. 3.
Find a common denominator.
The common denominator is 8.
Subtract the numerators and place the result over the denominator.
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Adding and Subtracting Fractions

9. Multiplying and Dividing Fractions
Example: Multiply or divide. 1.
Multiply the numerators.
Multiply the denominators.
Place the product of the numerators over the product of the denominators.
The sign rules for fractions are the same as those for integers. 2.
Write as a multiplication by the reciprocal of the divisor.
Multiply the numerators.
Multiply the denominators.
The result is negative since the signs are different.
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Multiplying and Dividing Fractions

10. The Order of Operations:
1. Perform all operations within grouping symbols as they occur from the inside out. Grouping symbols can be parentheses ( ), brackets [ ], the absolute value symbol | |, and the horizontal bar used in fractions and radicals.
2. Simplify all exponential expressions.
3. Do all multiplications and divisions as they occur from left to right.
4. Do all additions and subtractions as they occur from left to right.
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Order of Operations

11. Examples: Simplify. 1. 12 – 6 + 2 – 1 = 6 + 2 – 1 = 8 – 1 = 7
Subtract.
= 8 – 1
Add.
= 7
Subtract.
2. 3 · 5 – 2
= 15 – 2
Multiply.
= 13
Subtract.
Do subtraction within the grouping symbols.
3. 3 · (5 – 2)
= 3 · 3
The grouping symbols change the order of operations, changing the value of the expression.
= 9
Multiply.
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Examples: Simplify

12. 1. 20 3 2. 8 (2) = 18 – 4 = 14 Examples: Simplify. Multiply. Divide.
Add. 2. 8
Evaluate expressions inside grouping symbols from the inside out.
(2)
= 18 – 4
Simplify the exponential expression.
= 14
Subtract.
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Examples: Simplify

13. Examples: Simplify. 54 3 1.
Evaluate above and below the fraction bar. 9
Simplify the exponential expression. 18
Do left-most division. 2
Divide.
Subtract. 2.
= 5 – [(1 + 3)]2
Square root
= 5 – (4)2
Do addition within grouping symbols.
= 5 – 16
= 11
Simplify exponent.
Subtract.
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Examples: Simplify