(a) ∫ sin^2 3x cos 3x dx (b) ∫ cos x dx / √(sinx ) tentukan integralnya
Posted by andi telaumbanua on Feb 17, 2018 in Matematika |
Tentukanlah integral berikut:
-
∫ sin^2 3x cos 3x dx
-
∫ cos x dx / √(sinx )
Jawab:
1. Misalkan: u = sin 3x
Maka: du/dx=3cos3x
Sehingga : dx = du/(3 cos3x )
Atau: cos 3x dx = du/3
∫ sin^2 3x cos 3x dx = ∫ u^2 cos 3x du / (3 cos3x ) = 1/3 ∫ u^2 du = 1/3 1/3 u^3 + c = 1/9 (sin 3x)^3 + C
2. Misalkan: u = sin x
Maka: du/dx = cosx
Sehingga : dx = du/cosx
∫ cos x dx /√(sinx ) = ∫ (cosx ) /(u)^(1/2) du/cosx = ∫ (u)^(-1/(2 )) du = 1/(- 1/2+ 1) u^(1/2) + C = 2 √u + C = 2 √(sinx ) + C