1.8 introduction to equations i can solve equations using tables and mental math

1.8 INTRODUCTION TO EQUATIONS

I can solve equations using tables and mental math.

EQUATION

• A mathematical sentence that uses an equal sign

•Used to show the relationship between two quantities that have the same value

• True if the expressions on either side are equal

OPEN SENTENCE

• An equation is an open sentence if it contains one or more variables

•May be true or false depending on the value of the variables

PRACTICE

• Is the sentence true, false, or open?

• 7•8 = 54

• 12 – 4 = -2(-4)

• 2x – 14 = 36

SOLUTION OF AN EQUATION

• The value of a variable in an equation which makes the equation true

• Is x = 6 a solution to the equation 32 = 2x+12?

WRITING AN EQUATION

An art student wants to make a model of the Mayan Great Ball Court. The length of the court is 2.4 times its width. The length of the student’s model is 54 in. What should the width of the model be?

• Find key information

• What are we solving for?

• Create an equation with the given information.

• 2.4•w = 54

USING MENTAL MATH

• x + 8 = 12

• Think: what number plus 8 is 12?

• Solution: 4

• Check: 4 + 8 = 12

• Try this: = 9

USING TABLES• 5n + 8 = 48

• Make a table of values.

• Choose a starting value using mental math. Since 5(1) + 8 = 13, 1 is too low.

• Try 5.

• n = 8

n 5n+8 Value of 5n+8

5 5(5)+8 33

6 5(6)+8 38

7 5(7)+8 43

8 5(8)+8 48

ASSIGNMENT

•ODDS ONLY

• Pg.56 #7-11, 17-23, 27-33, 39, 41