Question attached!

Question

Question attached!

anonymous · Answer

attachment

anonymous · Answer

i keep gettin this wrong!

directrix · Answer

y' = - 8x^3 + 3x^2 + 2x Alternate forms at the link: http://www.wolframalpha.com/input/?i=derivative+of+y+%3D+%282x%5E2+%2B+x%29%28x+-+x%5E2%29

directrix · Answer

Let me check. You're doing the first times deriv of the second  and second times deriv of first -- factored form.

directrix · Answer

(x - x^2) (4x +1) + (2x^2 + x) (1 - 2x)

Look at that and see if If did the product rule correctly.

directrix · Answer

Are you supposed to leave the answer in simplifed factored form? x can be factored from (x - x^2) and so on.

anonymous · Answer

heres a example

anonymous · Answer

ah wait wrong problem

anonymous · Answer

attachment

directrix · Answer

I'm mixed up on what the red x and the zero out front mean.

directrix · Answer

Is this the original question ABOVE your work. I don't know how to read this input form.

screenshot20120221at5.33.51pm.png

directrix · Answer

Hey, I called for some help over here. Hold on.

anonymous · Answer

THANK YOU!

kinggeorge · Answer

Here's what my method would be: Use FOIL to find $(2x^2+x)(x-x^2) = -2x^4+x^3+x^2$ Then finding the derivative of that should be very straight forward.

kinggeorge · Answer

Namely, the derivative should be $-8x^3 +3x^2+2x$

kinggeorge · Answer

nevermind, I was doing the first problem, but the method should be the same for the second one you posted.

kinggeorge · Answer

$(4x^2 +x)(x-x^2)=-4x^4 +3x^3+x^2 $ So the derivative should be $-16x^3+9x^2+2x$

directrix · Answer

I think the issue is trying to figure out what the answer program will accept.

kinggeorge · Answer

Have you tried inputting simply $-16x^3+9x^2+2x$ or something of a similar form?

anonymous · Answer

nope i think they want a (...)(...)+(...)(...) type of answer

kinggeorge · Answer

In that case, $${dy \over dx} (4x^2+x)(x-x^2) = (8x+1)(x-x^2)+(4x^2+x)(1-2x)$$By the rule for deriving multiplications. However, it would appear you've already tried that. 

Are you sure they want a (...)(...)+(...)(...) type of answer?

anonymous · Answer

that one was the example problem the real one is at the top!:(

kinggeorge · Answer

My apologies, the derivative of the one at the top is$${dy \over dx} (2x^2+x)(x-x^2) = (4x+1)(x-x^2)+(2x^2+x)(1-2x) = -8x^3+3x^2+2x$$

kinggeorge · Answer

Did this help? Or is it still giving you strange error messages?

anonymous · Answer

still wrong but im gonna move on from it might be an instructor error thank you for the help!