Evaluating & Writing Alg Expressions

Evaluating Expressions

​Evaluating an expression means plug a number in for the variable.

This is also called "substitution"

• Example:

• Evaluate 2x + 5 when x = 4

• Use parenthesis 2( 4 ) + 5

• Use Calculator 8 + 5 .....Answer = 13

Multiple Choice

b² + 4
when b = 3

• 10
• 12
• 13
• 11

Multiple Choice

Evaluate the expression.   Let g = 3    h = 9 
4h + 2g + 4

• 42
• 46
• 34
• 58

Fill in the Blanks

Evaluate

$a+b^3-6$  

when a = 5 and b = 3

Fill in the Blanks

Evaluate:

$xz\div5$  

when x = 5 and z = 5

Multiple Choice

Evaluate when a = 15:
2(a - 5) + 2

• 22
• 27
• 14
• 7

Multiple Choice

c² + a; for a = 9 and c = 10

• 109
• 29

Multiple Choice

a² - b²
Evaluate if a=4 and b =2

• 4
• 20
• -4
• 12

Multiple Choice

6a - 3d
when a = 1, d = 2

• 3
• 12
• 1
• 0

Given a word phrase, you will have to translate (write) your own expression.

​

Writing your own Expression

Lets practice! YOU try!
(answers on next slide)

1) a number added to 5

2) the product of 8 and k

3) 8 divided by y

4) m decreased by 9

Lets practice! YOU try!

1) a number added to 5 5 + n

2) the product of 8 and k 8k

3) 8 divided by y 8/y

4) m decreased by 9 m - 9

Multiple Choice

Write an algebraic expression for the following:

the difference of 12 and d

• d - 12
• 12 + d
• 12d

• 12 - d

Math Response

Write an algebraic expression for the following:

x squared increased by 8

Type answer here

Correct Answer: x^2+8

Deg^°

Rad

Multiple Choice

a number added to 19

• 19-n
• 19+n
• 19/n
• 19n

Multiple Select

Which of the following words represent subtraction? (Check ALL that apply)

• Increase

• Less than

• Difference

• Quotient

Multiple Choice

Subtract a number from 10

• n - 10

• 10 + n

• $$\frac{10}{n}$$

• 10 - n

Multiple Choice

65 less than a number

• 65 - n

• n - 65

Multiple Choice

The total of twice a number and six.

• 2x + 6

• 2x - 6

• 2(x + 6)

• 2x(6)

Multiple Choice

Four times a number increased by 5 is

• 5 + 4n

• 5 x 4n

• 5(4n)

• 4n - 5

Multiple Choice

The quotient of a number and 20.

• $$\frac{x}{20}$$

• $$\frac{20}{x}$$

• 20x

• x + 20