Question

Here is how Noah solved his math problem. Do you agree with his method?

Explain why or why not.
Noah's method:
add 9 to each side
2(x - 9) = 10
2(x-9)+9 = 10 + 9
2x = 19
2x - 2 = 19-2
19
2
divide each side by 2
X=

Answer 1

No, because he kept adding to both sides rather than distributing 2 from x and 9 from the start

Answer 2

I don't agree with his method because he should've used the distribute method for the first step. For step 2, he would've needed to add 18 on both sides. Step 3 would be for him to divide both sides by 2, not subtract 2.

Explanation:

2(x - 9) = 10

step one: distribute

⇒ 2x - 18 = 10

step two: add 18 on both sides and then simplify

⇒ 2x - 18 + 18 = 10 + 18

⇒ 2x = 28

step three: divide both sides by 2

⇒
`(2x)/(2) = (28)/(2)`

⇒ x = 14