the derivative of f(x) = tcubed. I get the answer f'(x) = 3xcubed but I think the answer is supposed to be 3xsquared. (using the shortcut way). I'll put my workings below please wait and then please help!

Question

anonymous · Answer

$$\lim h \rightarrow 0 x - x ^{3} + 3x ^{3}h + 3xh ^{3} + h ^{3}/h$$

$$\lim h \rightarrow 0 3x ^{3}h = 3xh ^{3} + h ^{3}/h$$

$$\lim h \rightarrow 0 3x ^{3} + 3xh ^{2} + h ^{2}$$

(make h 0)
$$3x ^{3}$$

anonymous · Answer

Oh why didn't that come up as equation... annoying...

anonymous · Answer

x - xcubed + 3xcubedh + 3hcubedx + hcubed/h

3xcubedh + 3xhcubed + hcubed/h

3xcubed + 3xhsqured + hsquared

make h 0

3xcubed

amistre64 · Answer

t^3 derives to 3t^2

amistre64 · Answer

this whole cubed, squared, english stuff is confusing; use the '^' for exponent

anonymous · Answer

Hmmm yes that's what I thought, glad of the confirmation, but why can't I get that answer?

Okay I'll do that.

amistre64 · Answer

$$\frac{(x+h)^3-(x^3)}{h}$$

anonymous · Answer

x - x^3 + 3x^3h + 3h^3x + h^3/h 

3x^3h + 3xh^3 + h^3/h 

3x^3 + 3xh^2 + h^2

make h 0 

3x^3

amistre64 · Answer

$x^3+3x^2h+3xh^2+h^3-x^3$//h

$3x^2h +3xh^2 +h^3$//h

$3x^2 +3xh +h^2$ ; when h=0

$3x^2$

anonymous · Answer

I got the binomial theory wrong! 
Yes thankyou very much!

amistre64 · Answer

:)  i saw that