Conjugate reflexive verbs

Question

The KWIS has a question:

Nous ________ les cheveux. We brushed our hair
(HINT: Conjugate "se brosser" (to brush) in the compound past (Passé Composé))

Answer given: nous sommes brossé

But the text states:
Reflexive verbs always use être as the auxiliary verb in Le Passé Composé.
Note also that the verb must agree with the gender and number of the person.
i.e. taking an extra -e for women, and an extra -s for more than one person,

{In text: Conjugate reflexive verbs (+être) in the compound past in French (Le Passé Composé)}

Then should the answer not be:
nous sommes brossés ?

Accepted Answer

Jaap, 
it is worth heading back to the lesson and reading through the QandA below it, as there are previous explanations of this.
 ‘ Nous nous sommes brossé les cheveux ‘ is correct.
The direct object of se brosser in the sentence is ‘ les cheveux ‘ which follows the verb and therefore there is no agreement of the past participle. Agreement occurs when the direct object precedes the verb, which is most often the case with reflexive verbs, but not always - se brosser being one of the exceptions.
This question has come up often and it has been acknowledged the lesson needs a review to address this confusion. Until that is done, try the link below to Laura Lawless site for further explanation.
 https://www.lawlessfrench.com/grammar/agreement-with-pronominal-verbs/

Answer

Bonjour Jaap,It is confusing no doubt about that  --  French grammar tends to be quite pedantic.If you write "nous sommes brossés" this is meaningless because it leaves unanswered the question about what or who is being brushed? It simply translates as "We are brushed"To make it clear about what is being brushed then the grammar requires some sort of reflexive or reciprocal construction. Nous nous sommes brossés --> we brushed ourselves.I suggest that you revisit the lesson and pay particular attention to all of the links from that lesson to help enhance your understanding.Bonne continuationJim