"你一定要帮我！"

Translation: You must help me!

[MartinCarn4]

一定 means in general term " be sure ". But the correct answer was You HAVE to help me... "You Have to" in general term means 不得不。

[varigby]

又來了。別那麼龜毛。

In English, you must/have to help me mean the same thing and are interchangeable.

[DaveLommen]

Must sounds stronger.

[Zesul]

Would "你一定帮我！ " also be correct and mean the same?

[Bill496592]

You need 要 otherwise the sentence misses "command"/imperative tone.
https://www.chineseboost.com/grammar/five-uses-yao/

[MichaelLe3139]

Do we actually need 要 here, since "You must help me" & "You must WANT to help me" do mean differently to me.

[Bill496592]

要 in here is not for want. It is to form an imperative sentence. https://www.chineseboost.com/grammar/five-uses-yao/

[Handrisuselo]

What is "一定" here for? Does "一定要" mean "to have to; must"?

[BZH1423]

According to Duo, yes

[phoque]

This site is helpful to explain 'Commands' as part of the 5 uses for 要 https://www.chineseboost.com/grammar/five-uses-yao/

[Bill496592]

Oh yes i saw that too and copy and pasted for others lol

[CharlesEva1]

差不多， 可“必要”的意义有“must"或”need to"的感觉，“一定要”更有英语的“certainly will“。

[Jacques439990]

Yes

[xialuote1]

You really must help me

[samertabbal]

必要和一定要一样吗？

[BenoitMnar]

Why not using 必须，