Question

Turunan pertama f(x)= cos ² (3x + 6) adalah..
f'(x)=.....
pakai aturan rantai

Answer 1

Y = cos² (3x+6)
t = 3x + 6 --> dt/dx = 3
u = cos t --> du/dt = - t sin t
y = u² --> dy/du =2u

dy/dx = dy/du. du/dt.dt/dx
f'(x) = 2u. (-t sin t). 3
f'(x) = -3 (2) u t sin t= -6 cos (3x+6) . (3x+6). sin (3x+6)
f'(x) = - 3(3x+6) (2 sin(3x+6) cos(3x+6))
f'(x) = -3(3x+6) sin 2(3x+6)
..