1-6 Writing Expression (pgs 29-32) 1-9 Using formulas (pgs 40-43)

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# 1-6 Writing Expression (pgs 29-32) 1-9 Using formulas (pgs 40-43) - PowerPoint PPT Presentation

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

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### 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.. )
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