Using rate of change of a function to find an expression's value - Page 2

Integraluser · June 30th, 2018, 05:48 AM

Yeah, this is a literal translation:

If that rate of change of function f when x changes from x to x+h equals $\displaystyle 6x^2h - 3xh^2$, whereas h is a real number approaching 0, find f'(-2)

it has no answer choices, it needs the solution written with steps and so.

skipjack · June 30th, 2018, 07:54 AM

Was the textbook written by a committee rather than a professional mathematician?

Integraluser · June 30th, 2018, 12:21 PM

Yeah a committee I assume, 4 doctors administrated its authorship and 6 have written it, 3 among of whom are doctors according to the book. It's even the official book by the ministry of education being taught in schools, not sure why this mistake is there twice.

Doesn't matter actually, it's fine since I've got your opinions regarding it and we agreed on the same point (that it should be "change in y" rather than "rate of change"). I might of tell someone who can do something about it so that it gets fixed.

skipjack · July 1st, 2018, 01:37 AM

Even if "rate of" is omitted, the questions are flawed.

Integraluser · July 1st, 2018, 07:30 AM

Why so?

skipjack · July 1st, 2018, 10:56 AM

Try to find a function with the specified property.

Integraluser · July 2nd, 2018, 10:42 AM

Oh alright, maybe the nearest function would be $\displaystyle x^3$ but you are right. I think they made it like this just to make it suit their wanted idea.

June 30th, 2018, 05:48 AM	#11
Integraluser Newbie Joined: Jun 2018 From: Jordan Posts: 19 Thanks: 0	Yeah, this is a literal translation: If that rate of change of function f when x changes from x to x+h equals $\displaystyle 6x^2h - 3xh^2$, whereas h is a real number approaching 0, find f'(-2) it has no answer choices, it needs the solution written with steps and so.
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June 30th, 2018, 07:54 AM	#12
skipjack Global Moderator Joined: Dec 2006 Posts: 19,865 Thanks: 1833	Was the textbook written by a committee rather than a professional mathematician?
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June 30th, 2018, 12:21 PM	#13
Integraluser Newbie Joined: Jun 2018 From: Jordan Posts: 19 Thanks: 0	Yeah a committee I assume, 4 doctors administrated its authorship and 6 have written it, 3 among of whom are doctors according to the book. It's even the official book by the ministry of education being taught in schools, not sure why this mistake is there twice. Doesn't matter actually, it's fine since I've got your opinions regarding it and we agreed on the same point (that it should be "change in y" rather than "rate of change"). I might of tell someone who can do something about it so that it gets fixed. Last edited by Integraluser; June 30th, 2018 at 12:25 PM.
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July 1st, 2018, 01:37 AM	#14
skipjack Global Moderator Joined: Dec 2006 Posts: 19,865 Thanks: 1833	Even if "rate of" is omitted, the questions are flawed.
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July 1st, 2018, 07:30 AM	#15
Integraluser Newbie Joined: Jun 2018 From: Jordan Posts: 19 Thanks: 0	Why so?
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July 1st, 2018, 10:56 AM	#16
skipjack Global Moderator Joined: Dec 2006 Posts: 19,865 Thanks: 1833	Try to find a function with the specified property.
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July 2nd, 2018, 10:42 AM	#17
Integraluser Newbie Joined: Jun 2018 From: Jordan Posts: 19 Thanks: 0	Oh alright, maybe the nearest function would be $\displaystyle x^3$ but you are right. I think they made it like this just to make it suit their wanted idea.
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