tolong dibantu beserta jalannya. Jika f (x) = x sin 3x, maka f' (π/4)=

Turunan

f(x)= x . sin 3x
f(x)= u v --> f'(x) = u'v + uv'

f'(x) = 1(sin 3x) + (x)(3cos 3x)
f'(x) = sin 3x + 3x cos 3x
f'(π/4)= sin (3π/4)   + 3(π/4) . cos (3π/4)
f'(π/4) = ¹/₂ √2  + ³/₄ π . (- ¹/₂√2)
f '(x)= ¹/₂ √2 ( 1 - ³/₄ π)
f '(x) = ¹/₂ √2 (¹/₄ π)
f '(x)= π( ¹/₈√2)