Transcript 4 – 1 Writing Equations and Expression (pg 150-151)

1-6 Writing Expression (pgs 29-32)
1-9 Using formulas (pgs 40-43)
9P3:Describe problems using symbolic representation
What is the difference between an equation and an
expression???
Expressions
 combination of variables, numbers, and operations.
 can be simplified by combining like terms
(ex: 2xy + 4x +3 or 2a + 3a)
Equations
 two expressions that are equal.
 Both sides have the same value.
 Can be solved to find the value that works( most
equations only have one number that makes them
true.
(ex: 2x +3 = 4x +5) ← x= -1 no other number works
Things to note:
 Watch subtraction problems: x - 2 is
different than 2 – x
 Remember your vocabulary… (What words
mean + - × ÷)
 Put the equal sign in the equation where
you see the word is (or other forms such as
has, had, was, were, etc.. )
Which words/symbols mean + - × ÷
+
-
×
plus
minus
times
difference
product
and
from
at
added to
less
double,
greater than
less than
triple, etc.
more than
twice
increased by fewer than
decreased by of (fractions &%)
total
take away
× • ( ) ab
Sum
+
÷
quotient of
goes into
per
divided by
÷
a a/b
b
Write an expression for the following
1) The sum of a number and 3
n+3
2) three less than twice a number
2n - 3
3) 2 times the sum of 8 and a number
2(n+8)
4) Let s be Sue’s age. If Sue is 10 years older than Roy, write
an expression for Roy’s age
s - 10
Use formula to solve problems
 The speed of an airplane (a) is the Mach number
(M) times the speed of sound (s).
What equation represents this relationship?
a=Ms
If an airplane is traveling at Mach 1.5 and the
speed of sound is 720mi/hr, what is the speed of
the airplane?
Step 1: write formula
a =Ms
Step 2: Substitute
a =1.5*720mi/hr
Step 3: simplify/label units
a = 1080 mi/hr
Assignment
 1-6/30/ 2-48eoe, 62-72 e
 1-9/42-43/ 2-22e, 26-34e
Marker board
Pg 30
3
23
25
31
39
43
45
67
71
Pg 42
3
13
17
27