Read the sentence. the british defeat of the mahdist forces at omdurman finally brought an end to the shameful and horrific slave trade. this sentence does not maintain a formal style and tone because it uses casual language. is completely objective. uses charged language. is a choppy sentence.

The answer to your question would be that the sentence does not mantain a formal style and tone because it uses charged language.  The statement is not an objective fact, it is charged with subjective language instead ("shameful", "horrific").

Formal writing employs impersonal and precise language. Writing formally and objectively requires a writer to write without sharing his personal point of view. What is more, formal and objective writing should also avoid the use of the first person or the personal point of view.

because i have already answered your question several times, answering it again would be superfluous.

by elena

the answer would be, she updates her online profiles regularly and participates in work-related online discussions.