#Showing increasing functions

30 messages · Page 1 of 1 (latest)

last parcel
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Any help is greatly appreciated

final shell
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increasing means f'(x)>=0

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so differentiate and u get 5x^4 - 30x^2 + 50

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are you stuck there?

last parcel
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No I just didnt think of that

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What would you do from there?

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solve?

final shell
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no

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you have to prove that that is always >=0

last parcel
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How would u do that?

final shell
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have a go first

last parcel
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Alright

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thanks brother

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Diff of 2 squares?

final shell
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how will that prove its bigger or equal to 0

last parcel
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discriminant

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its below 0 I did it

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But then you know the final point

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thats where I struggle

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Like that shows there are no real roots

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so no x values

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So then from there idrk how to say its always an increasing function

final shell
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ok thats one way

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since its a positive x^4 graph then if there are no real roots it must be above the x-axis for all x thus 5x^4 - 30x^2 + 50 will never give a negative output

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so >=0

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or what you could do is complete the square

last parcel
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Oh I see

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like say y=x^2

final shell
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yep

last parcel
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Thanks so much man