Transcript Solve Two-Step Equations

Do Now 10/23/09
 Take out HW from last night.
 “Food Consumption” worksheet
 Copy HW in your planner.
 Text page 122-123, #8-18 evens, #24-32 evens, #36
 In your journal, answer the following question.
 Sally Sue just received her cable bill from Comcast. The bill for
the month is a total of $114.50. Comcast charges $5.00 for
each movie ordered “On Demand.” Sally Sue can’t remember
how many “On Demand” movies she ordered in the month? If
Sally Sue’s normal bill is $89.50, how many “On Demand”
movies did she order?
 Can you think of an equation to help you solve this question?
Use the variable “m” for movies.
“You Are What You Eat”
25 year-old man
66
+ (13.7)(180)(0.45)  +1109.7 weight
+ (5)(70)(2.54) 
+ 889
height
– (6.8)(25) 
- 170
age
+ (30)(11.3) 
+ 339
basketball
+ (30)(17) 
+ 510
running
+ (2000)(0.1) 
+ 200
digestion
Total Calories Needed 2943.7
25 year-old woman
+ (9.6)(120)(0.45) 
+ (1.7)(64)(2.54) 
– (4.7)(25) 
+ (45)(7.4) 
+ (30)(6.5) 
+ (2000)(0.1) 
655
+518.4
+ 276.352
- 117.5
+ 333
+ 195
+ 200
Total Calories Needed 2060.252
weight
height
age
aerobics
walking
digestion
Objective
 SWBAT solve two-step equations using
algebra
Did you know your cell phone bill
can be calculated from a two-step equation?
Equation
2 s + 8 = 20
Left side
‘s’ has to be 6 in order
to make the equation
balanced.
Like a scale, the left
side and right side must
be the same in order to
be balanced!
Right side
Equation mathematical sentence
with an equal sign
Like a scale,
both sides must be
EQUAL in order
to be balanced.
Section 3.1
“Solve Two-Step Equations”
How can you get the “unknown” by itself?
3x + 5 = -19
“Undo” operations by using the INVERSE (opposite)
operations to both sides of the equation.
Solving Two-Step Equations
STEP 1STEP 2STEP 3STEP 4-
“Undo” addition and/or subtraction.
“Undo” multiplication and/or division.
Solve for the variable.
Check your work.
Solving Two-Step Equations…
Isolate the variable! Get ‘x’ by itself.
To get the ‘x’ by
itself first get rid
of “adding 5.”
3x + 5 = -19
-5
-5
Do the opposite.
“Subtract 5.”
Whatever you do to
one side of the equation
you must do the other side.
To get the ‘x’ by
itself get rid
of “multiplying by 3.”
Do the opposite.
“Divide by 3.”
3x = -24
3
3
x = -8
Check Your Work!
3x + 5 = -19
x = -8
3(-8) + 5 = -19
Are both sides equal?
“Two-Step”
Millionaire
Homework
Text page 122-123, #8-18 evens, #24-32 evens,
#36