a) g(x) = x^3 – xakarx + 2sinx + cosx + 1
b) g'(x) = sin^2 a – cos a + cos^2 a + 2 sin a
Hitunglah nilai dari g'(phi/6) dari :
Jawab:
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