1. Jika f(x) = sin x cos 3x maka f'(phi/6) = 2. turunan pertana dari y = sin 1/x adalah...

No 1 f(x) = sinx cos3x
Misalkan u = sinx maka u' = cosx
dan
v= cos3x maka v' = -3cos3x

sehingga f'(x) = u'v + v'u
= (cosx) (cos3x) + (-3cos3x) (sinx)

maka
f'(π/6)= cos(π/6)cos3(π/6) + (-3cos3(π/6)(sin(π/6))
= Cos30° ( cos90° ) + (-cos90°)(sin90°)
= ½√3(0) + (0)(1)
=0