Question

Holly finds that (11m – 13n + 6mn) – (10m – 7n + 3mn) = m – 20n + 9mn. What error did Holly make? a)he only used the additive inverse of 10m when combining like terms. b)She added the polynomials instead of subtracting. c)She only used the additive inverses of –7n and 3mn when combining like terms. d) She did not combine all like terms.

Answer 1

answer A

Explanation:

Answer 2

a) She only used the additive inverse of 10m when combining like terms.

Explanation:

Given : Holly finds that
`(11m-13n+6mn)-(10m-7n+3mn)=m-20n+9mn`

First we open the bracket by multiplying minus sign in it, we get

`11m-13n+6mn-10m+7n-3mn`

Combining like terms we get, we get

`11m-10m-13n+7n+6mn-3mn=m-6n+3mn` → correct answer.

When we compare the correct answer to the answer given by Holly, the first term is same in both the answers,

Therefore, She only used the additive inverse of 10m when combining like terms.