Hasil dari integral Sin 3x Cos 4x dx, batas atas= π/3 batas bawah= 0 ?

Int (sin 3x cos 4x) dx
= Int (cos 4x sin 3x) dx
= Int (1/2 (sin (4x + 3x) - sin (4x - 3x)) dx
= Int (1/2 sin 7x - 1/2 sin x) dx
= 1/2 . -1/7 cos 7x - 1/2 . -cos x | batas 0 sampai π/3
= -1/14 cos 7x + 1/2 cos x | batas 0 sampai π/3
= 1/2 cos x - 1/14 cos 7x | batas 0 sampai π/3
= (1/2 cos π/3 - 1/14 cos 7π/3) - (1/2 cos 0 - 1/14 cos 0)
= (1/2 . 1/2 - 1/14 . 1/2) - (1/2 . 1 - 1/14 . 1)
= 1/4 - 1/28 - 1/2 + 1/14
= (7 - 1 - 14 + 2)/28
= -6/28
= -3/14