Question

Marcel made an error when he used the distributive property to solve the problem shown. Which sentence describes the error?

Answer 1

The answer to this is step 2 because they multiplied when they should of subtracted the 10 and the 12.

Answer 2

Answer:

In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10.

Step-by-step explanation:

Consider the provided expression.

$90\cdot x-90\cdot 12$ when x=10

Solve the above expression as shown:

Step 1:

$90\cdot x-90\cdot 12=90(x-12)$

Step 2: Substitute x=10.

$90\cdot x-90\cdot 12=90(10-12)$

Step 3: Open the parenthesis.

$90\cdot x-90\cdot 12=900-1080$

Step 4: Simplify

$90\cdot x-90\cdot 12=-180$

From the above calculation we can say that the error is:

In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10.