Transcript Nice to see you! Cell phones off & in backpack pencil & composition

Please have out
notebook, pencil, white board marker
Warm-up
Translate the following into algebraic expressions
1. Eleven more than a number divided by 3.
2. Three increased by 12 times a number.
3. 3 times the difference of a number and 12.
4. Half of a number plus 3.
Remember to write out obj & prof & level
Answers to warm-up
1.
2.
3.
4.
11 + x / 3
3 + 12x
3(x-12)
x/2 + 3
OBJ: TO write alg expressions using # &
variables & to use the order of operations
1.1 numbers & operations
4 Basic operations:
1. Addition: sum, added to, plus,
increased by
2. Division: half of, quotient, divided by,
split into
3. Subtraction: less, minus, decreased by,
subtract, difference, taken away
4. Multiplication: times, product, doubled,
multiplied by
1.2 Variables in Expressions
• Variable: a letter used to represent a number
• Value of the variable: the number the variable
represents
• Algebraic expression: a collection of numbers,
variables, operations, & grouping symbols.
• Evaluating an expression: solving the
expression by inputting a number in for the
variable(s)
Algebraic expression
8y
16a/b
4r + 2
Meaning
8 times y
16 times a then divide
by b
4 times r then plus 2
Brain Break
• You have 10 seconds to get up & change
seats w/someone across the room
3 simple steps to help you evaluate
expressions correctly
1. Write the algebra expression
2. Substitute values for the
variable(s). x = 2
3. Simplify the numerical
expression
4x
4(2)
8
examples
•
•
•
5x + 4y, when x = 3 and y = 2
5x + 4y
write the expression
5(3) + 4(2)
substitute the #s
15 + 8 = 23
simplify
•
•
•
•
X + (2x -1) when x = 3
X + (2x -1)
write the expression
3 + (2*3 – 1)
substitute the #
3 + (6 – 1)
simplify
3+5=8
simplify
Algebraic equations used in real life
Area of a rectangle
A = LW
• If L = 4 cm and W = 14 cm, what is the area?
• A = 56 cm2
Distance
distance = rate(time)
d = rt
• If a car travels 15 mph for 4 hours, how far
did the car travel?
• D = 60 miles
White boards out
Try these
1. x – 9 when x = 21
2. xy when x = 3 and y = 2
3. Distance d = rt
•
Rate = 60 mph
time = 2 hrs.
4. Area of a rectangle
Answers
1) 12
2) 6
3) D = 120 Miles
4) A = 12 in2
2 in.
6 in.
Any questions
• Homework
• Pg. 5 #15-23 odds
• Pg. 11-12 #7-19 odds