G8

Copyright © Swun MathCopyright © Swun Math Grade 8 Unit 4 Lesson 6 P TE

Challenge Problems

Directions: Describe and correct the error in the following equations.

1. ─2(x – 4) = 10

Step 1: ─2x – 4 = 10

Step 2: ─2x = 14

Step 3: x = ─ 7

Solution: In Step 1, when the ─2 is distributed, it

should be − 2 푥푥+ 8 = 10. The correct solution:

− 2 (푥푥− 4 )= 10

− 2 푥푥+ 8 = 10

− 2 푥푥= 2

푥푥=− 1

2. 14 – 3(x + 1) = 22

Step 1: 11(x + 1) = 22

Step 2: 11x + 11 = 22

Step 3: 11x =11

Step 4: x = 1

Solution: In Step 1, the 3 must be distributed to (x + 1)

before it is subtracted from 11. The correct solution:

14 − 3 푥푥−3 = 22

11 − 3 푥푥= 22

− 3 푥푥= 11

푥푥=−11 3 표표표표− 323

Extension Activity

* MP1: Make sense of the problem and persevere in solving it.

* MP4: Apply mathematics in everyday life.

Write an equation that meets the following criteria:

1. 
   

   Uses the distributive property

   
   


2. 
   

   Has negative coefficients

   
   


3. 
   

   Must collect like terms

   
   


4. 
   

   Has a solution of −2