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

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 + - ×÷ 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

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