Question

1. Liam is solving the following equation 12a - 4(5a - 1) = 2(3a + 6) - 4a. The result of each

step of his solution is shown below.
12a - 4(5a - 1) = 2(3a + 6) - 4a
12 - 20a + 4 = 6a + 12 - 4a
-8a + 4 = 2a + 12
-6a = 8
a = -4/3
Describe the error AND solve correctly.

Answer 1

Explanation:

Liam did not include 12a in line- two

Step one:

given the expression

`12a - 4(5a - 1) = 2(3a + 6) - 4a`

let us trace the solution line by line

`line-one=12a - 4(5a - 1) = 2(3a + 6) - 4a\\\\line-two=12a - 20a + 4 = 6a + 12 - 4a\\\\`

collect like terms

`line -three=-8a-6a +4a=12 +4\\\\line-four=-14a+4a=16\\\\line-five=-10a=16`

divide both sides by -10 we have

`line-six= a=16/10\\\\line-seven=a=-8/5`