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15. [-/2 Points] DETAILS SCALCET8 3.4.081. MY NOTES A Cepheid variable star is a star whose brightness alternately increases and decreases. For a certain star, the interval between times of maximum brightness is 5.4 days. The average brightness of this star is 4.0 and its brightness changes by +0.45. In view of these data, the brightness of the star at time t, where t is measured in days, has been modeled by the function B(t) = 4.0 + 0.45 sin(2nt (a) Find the rate of change of the brightness after t days. dB dt (b) Find, correct to two decimal places, the rate of increase after one day. dB = dt (Alt + A)3. [-/3 Points] DETAILS SCALCET8 3.4.505.XP. Find the derivative of the function. y = + 5 3 y'= 4. [-/3 Points] DETAILS SCALCET8 3.4.506.XP. Find the derivative of the function. y = V1+ 26X y' =1. [-/3 Points] DETAILS SCALCET8 3.3.501.XP. Differentiate. f(x) = 4x# - 9 cos(x) f ' ( x ) = 2. [-/3 Points] DETAILS SCALCET8 3.3.502.XP. Differentiate. f(x) = 4v x sin(x) f ' ( x ) = 3. [-/3 Points] DETAILS SCALCET8 3.3.022. Find an equation of the tangent line to the curve at the given point. y = Ze* cos(x), (0, 2) y