G8

Copyright © Swun Math Grade 8 Unit 2 Lesson 9 C TE

Input/Model

(Teacher Presents)

Directions: Solve. Determine if the solution is a rational or irrational number.

1. 푚푚^2 = 25

Solution:

Step 1: 푚푚^2 = 25

Step 2: √푚푚^2 =√ 25

Step 3: (^) √푚푚⋅푚푚=√ 5 ⋅ 5 or √푚푚⋅푚푚=�(− 5 )⋅(− 5 )
Step 4  Solution 1: 푚푚= 5
Solution 2: 푚푚=− 5
Step 5: Solution is 푚푚= ±5 and it is a rational number.
Talking points:

• Begin by identifying the unknown.


• Then, understand that it is a squared problem indicated by the exponent.


• To undo this power, take the square root both of sides of the equation to keep the equation equivalent.


• Since a square number and the square root of the number are inverse, they “undo” or cancel each other out.


• Solve using the steps.

2. 푏푏^2 = 11

Solution:

Step 1: 푏푏^2 = 11

Step 2: √푏푏^2 =√ 11

Step 3:√푏푏⋅푏푏=√ 11 11 is not a perfect square

Step 4: 푏푏= ±√ 11

Step 5: The solution is 푏푏= ±√ 11 ; an irrational number.