Question

Callie solved this one-variable equation. When she was done, she tried to verify her answer, but found that it was wrong. Can you find her mistake? 1 2 (4k + 8) = 10 1. 2k + 16 = 10 2. 2k = −6 3. k = −3

Answer 1

2(4k+8)=10
8k+16=10 (she said 2k instead of 8k)

To continue solving, subtract 16 from both sides. That would give you 8k= -6. Then divide both sides by 8, and get -6/8 which equals -3/4.

Answer 2

Mistake found in step 1

Explanation:

Callie solved this one-variable equation. When she was done, she tried to verify her answer, but found that it was wrong.

`2(4k + 8) = 10`

Step 1:
`2k + 16 = 10`

Step 2:
`2k = -6`

Step 3:
`k = -3`

In step 2, 2 is distributed inside the parenthesis

`2(4k + 8) = 10`

When 2 is multiplied inside the parenthesis, the equation becomes

`8k + 16 = 10`

She forgot to multiply 2 with 4k

So the mistake is in step 1