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# Calculus/math

Question
sir, plz tell me how
if f(x)=cos3x ...how it is neither increasing nor decreasing on(0,pie/2)

sirrr ..plz   send answer directly to my email ...i m nt able to click on your links ...so plz

I'm not sure how to reply directly to your email, but here it is in AllExperts.

If the function is f(x) = cos(3x), and the interval is (0,pi/2),
let's look at the derivative.

It can be seen that f'(x) = -3*sin(3x). Since sin(0) = 0 and sin(3x) is positive on (p,pi/2),
the function is increasing over the whole interview with an inflection point at x=0.

Calculus

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#### Scotto

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