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onegirl
Group Title
Find the indicated derivative of the function f(x) = cosx^2, find f''(x)
 one year ago
 one year ago
onegirl Group Title
Find the indicated derivative of the function f(x) = cosx^2, find f''(x)
 one year ago
 one year ago

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satellite73 Group TitleBest ResponseYou've already chosen the best response.0
\[2\cos(x)\sin(x)\]is your first derivative take the derivative of that one, using the product rule
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
@satellite73 it will be 2cos(x)sin(x)
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
@genius12 so the derivative of 2cos(x) sin(x) , and i got 2 cos(2x)
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
@satellite73 ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
@jazy should i now take the derivative of 2 cos(2x) ? or
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
which one : dw:1362427439289:dw
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
so, the first one in my diagram ?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
oke, to get the first derivative of f(x) we can use the cain rule hint : derivative of x^2 = 2x derivative of cos =  sin
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
yea i got it the first derivative will be 2 cos(x) sin (x) right?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
so, derivative of f(x) = cosx^2 > f ' (x) = 2x(sinx^2) = 2x sinx^2
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
so then i take the derivative of 2x sinx^2 ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
okay after i take the derivative of 2x sinx i get 2 cos(2x) so then i take the derivative of 2 cos(2x) right?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
use the product rule to get the 2nd derivative : use the formula : f '' = u'v + uv' assuming that u=2x > u' = ... ? v = sinx^2 > v ' = ... ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
how would i do it?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
can u show it?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
do u know derivative of 2x ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
its 2 right?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
yes, that's right also, sinx^2 ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
okay hold on
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
but where does sinx^2 come from i got 2 cos(x) sin(x) ??
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
for my derivative of cosx^2
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
f(x) = cosx^2 > f ' (x) = 2x(sinx^2) = 2x sinx^2
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
it just the first derivative of f(x), now we have to deriv again to get f " then, use the product rule
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
so now i need to find the derivative of sin^x right? since we found 2x which we got 2
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
and i got cos (x) sin(x)
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
so it will be 2 cos(x) sin(x) right?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
2x sinx^2 let u=2x > u' = 2 v = sinx^2 > v ' = 2xcoscx^2
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
sorry, it should v' = 2xcosx^2
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
okay so how would i set it up in the formula ?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
f " = u'v + uv' f " = (2)sinx^2 + (2x)2xcosx^2 = 2sinx^2  4x^2cosx^2
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
so what do i do next?
 one year ago

RadEn Group TitleBest ResponseYou've already chosen the best response.0
nothing, it is clear :)
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
okay so the f'''(x) will be 2sinx^2 = 4x^2 cosx^2 ?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
i meant f''(x)
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
are you there?
 one year ago

onegirl Group TitleBest ResponseYou've already chosen the best response.0
@RadEn so thats the final answer?
 one year ago
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