Find the coefficient of the squared term in the simplified form for the second derivative, f "(x) for f(x) = (x3 + 2x + 3)(3x3 − 6x2 − 8x + 1). Use the hyphen symbol, -, for negative values.

Question

tmagloire1 · Answer

@ganeshie8 @Directrix

tmagloire1 · Answer

(x^3 + 2x + 3)(3x^3 − 6x^2 − 8x + 1) sorry i forgot about exponents

ganeshie8 · Answer

I think, I would just use wolfram as I don't see any immediate obvious trick... and finding the second derivative by hand is a pain

tmagloire1 · Answer

This is what wolfram gave me for the second derivative : 
2 (-34-6 x-12 x^2-60 x^3+45 x^4)

tmagloire1 · Answer

Then i got the squared term as -24 once i foiled

tmagloire1 · Answer

is that really all there is to this problem?

parthkohli · Answer

It seems that there is only one way to generate an $x^4 $ in the expansion of the original polynomial.

parthkohli · Answer

Which is of course by combining $x^3$ of the first and the $-8x$ of the other.

parthkohli · Answer

And there is another - 2x * 3x^3.

tmagloire1 · Answer

Why is x^4 relevant now? Aren't we just trying to find x^2?

parthkohli · Answer

Because the only way you can get an $x^2$ is by double-differentiating an $x^4$ term.

tmagloire1 · Answer

Ohh alright i understand