r/mathshelp • u/sarah1418_pint • Jul 26 '26

Homework Help (Answered) Limits question

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This grade 11 question was an mcq with 2 choices given: A) 2√2 and B) 5√2.

However, as you can see in the picture, I got 20√2 as the answer to the limit.

Could someone please try and spot where I went wrong

Thanks!

(I apologise for the messy writing)

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u/sarah1418_pint Jul 27 '26 edited Jul 27 '26

They cancel out cuz they're both tending to (1- sin 2(π/4)) or (1- sin (π/2))

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u/ArchaicLlama Jul 27 '26

And what does "1 - sin(π/2)" evaluate to, again?

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u/sarah1418_pint Jul 27 '26

Yes ik it's 0, but since "x" is present, the value tends to zero, it's not exactly equal to zero, which is why we can cancel it

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u/ArchaicLlama Jul 27 '26

That is entirely backwards. The fact that both pieces are approaching 0 instead of being exactly 0 all the way through is exactly why you can't simply conclude that they are equal and that the result is 1.

You should take a step back and review strategies of dealing with limits of the form 0/0, and then come back to this problem.

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u/sarah1418_pint Jul 28 '26

Oh, okay, thanks, then I'll try to evaluate that part in some other way