Mathematics 95 Online
OpenStudy (anonymous):

OpenStudy (anonymous):

yeah what's up?

OpenStudy (anonymous):

whats the question

OpenStudy (anonymous):

\[d ^{2}x/dt ^{2} \] if dx/dt= 9x sin x

OpenStudy (anonymous):

use the product rule

OpenStudy (anonymous):

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

OpenStudy (agreene):

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

OpenStudy (anonymous):

same procedure

OpenStudy (anonymous):

use your first derivative to find the second

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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.

OpenStudy (agreene):

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

OpenStudy (zarkon):

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

OpenStudy (anonymous):

use your first derivative to find the second

OpenStudy (anonymous):

watch your signs its - not +

OpenStudy (anonymous):

so how do i take the derivative implicitly?

OpenStudy (zarkon):

have you done implicit differentiation?