Derivatives again: y = (x^2 - 6)(x^3 + 2)

scrum

Junior Member
Joined
Oct 11, 2007
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55
Okay I have to get the derivative of this.

672242img1.gif


I multiply it out and get
x^6 -6x^3 +2x^2 -12

and differentiate to

6x^5 -18^2 +4x

and it says i'm wrong, but i don't see where i'm doing anything wrong. i've done it over 3 times and i'm still wrong.
 
Re: Derivatives again.

scrum said:
Okay I have to get the derivative of this.

672242img1.gif


I multiply it out and get
x^6 -6x^3 +2x^2 -12

and differentiate to

6x^5 -18^2 +4x

and it says i'm wrong, but i don't see where i'm doing anything wrong. i've done it over 3 times and i'm still wrong.

\(\displaystyle \L y = (x^2 - 6)(x^3 + 2)\)

Use the product rule

\(\displaystyle \L y' = \frac{d}{dx}(x^2 - 6)(x^3 + 2) \,+\, (x^2 - 6)\frac{d}{dx}(x^3 + 2)\)

\(\displaystyle \L y' = (2x)(x^3 + 2) \,+\, (x^2 - 6)(3x^2)\)

Simplify if you want to.

John
 
regarding the multiplication of the first two terms ...

x<sup>2</sup> times x<sup>3</sup> is x<sup>5</sup>, not x<sup>6</sup>.
 
skeeter said:
regarding the multiplication of the first two terms ...

x<sup>2</sup> times x<sup>3</sup> is x<sup>5</sup>, not x<sup>6</sup>.
oh yea...

dude i need an algebra refresher or something. I'm gonna try to help ppl in the algebra section or something.
 
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