Integral dari : (a) ∫ ctg x dx (b) ∫ (x dx) /(1- x^2 )
Posted by andi telaumbanua on Feb 17, 2018 in Matematika |
Tentukanlah Integral dari :
-
∫ ctg x dx
-
∫ (x dx) /(1- x^2 )
Jawab:
1. ctg x = cosx/sinx
misalkan: u = sin x
maka: du/dx= cosx
Sehingga: dx = du/cosx
∫ctg x dx = ∫ cosx / sinx dx = ∫( cosx /u) ( du/cosx) = ∫ du / u = ln|u| + C = ln| sinx | + C
2. misalkan: u = 1- x^2
maka: du/dx = -2x
Sehingga: dx = du /(-2x)
∫ (x dx) /(1- x^2 ) = ∫ (x/u) [du /(-2x)] = 1 /(-2) ∫ du /u = 1/(-2) ln |u| + C = 1/(-2) ln |1- x^2 | + C