derivative problem help please.

Question

anonymous · Answer

yeah what's up?

anonymous · Answer

whats the question

anonymous · Answer

$$d ^{2}x/dt ^{2} $$ if dx/dt= 9x sin x

anonymous · Answer

use the product rule

anonymous · Answer

i get that i just don't understand the second derivative of x.

agreene · Answer

f"(x) = d/dx f'(x)

anonymous · Answer

same procedure

anonymous · Answer

use your first derivative to find the second

anonymous · Answer

the answer would be 9x((cos(x))+9(sin(x)) because of the product rule :)

anonymous · Answer

yes i understand that. what i mean is that when you take the second derivative of x, it should not equal 1 like it would in the first derivative. i don't know how to find that.

agreene · Answer

f'(x) = 9(sinx+xcosx)

use that and find it's derivative to find f"(x)
for reference:
f"(x) = 18cos(x)-9xsin(x)

zarkon · Answer

the way you wrote the problem you will have to take the derivative implicitly, treating x as a function of t

anonymous · Answer

use your first derivative to find the second

anonymous · Answer

watch your signs its - not +

anonymous · Answer

so how do i take the derivative implicitly?

zarkon · Answer

have you done implicit differentiation?