Question

what is the second derivative of y = 3/(4x^-3)
a -3.6
b -1.84
c 2.4
d 4.5

Answer 1

Well, what do you have to start out with? It's 3 * (4x^-3)^-1. Can you take this first derivative?

Answer 2

re-write as
\[y=\frac{3}{4}x^{3}\]

Take the 2nd derivative, then plug in the x value they gave you (I assume x=1?)

Answer 3

yes x =1

Answer 4

kingkos, do you know how to find the second derivative?

Answer 5

no not yet lesson for today of my prof

Answer 6

oh okay. So did you see the way I worked the first derivative? I'll clean it up a little bit so it's more readable.

Answer 7

do you know how to take the derivative? If so , do so

Answer 8

yes thats the formula i write in my notebook but im confuse of your -4 how did u get that?

Answer 9

\[[9\times(4x ^{-3}-3)^{-2}*(-12x ^{-4})\]

I screwed up a bit on that last part in an earlier message, sorry. But I think this is correct.

Answer 10

So you take the derivative of the outer part and then multiply by the derivative of the inner part.

Answer 11

It just gets messier from here.

Answer 12

crap, I pasted in the equation, but the whole thing isn't showing up.

Answer 13

nevermind! My brain isn't working AT ALL today. Yeah, it's 4.5

Answer 14

I believe y = 3/(4x^-3) means
\[ y=\frac{3}{4x^{-3}} \] which is equivalent to
\[ y=\frac{3}{4} x^{3} \]
Use the power rule
\[ \frac{dy}{dx}= \frac{9}{4} x^2 \]
the 2nd derivative is
\[ \frac{d^{2}y}{dx^2}= \frac{18}{4} x \]
Evaluate at x=1 to find 4.5

Answer 15

sorry phi and kingkos, I'm a total retard today!

Answer 16

Everyone has a bad hair day every now and again.

Answer 17

This is what happens when I visit this site early in the morning, LOL

Answer 18

things phi dont worry i after i finish my homework i will study hard

Answer 19

its ok brinethery same with me