Tolong carikan no 30 31 lah ya plisss beserta jalan ya!!

31. misal u = 1 - 5x
du = -5 dx
dx = du/-5
u = 1 - 5x
5x = 1 - u
x = (1 - u)/5

18x (1 - 5x)^7 dx
18(1 - u)/5 u^7 du/-5
-(18/25) (1 - u) u^7 du
(-18/25) u^7 - u^8 du
integralkan
(-18/25) (1/7+1)u^(7+1) - (1/8+1)u^(8+1) + C
(-18/25) (1/8)u^8 - (1/9)u^9 + C
(-18/25)(1/72)u^8(9 - 8u) + C
(-1/100) u^8 (9 - 8u) + C
(-1/100) (1 - 5x)^8 (9 - 8(1 - 5x)) + C
(-1/100) (1-5x)^8 (9-8+40x) + C
(-1/100) (1-5x)^8 (1+40x) + C
pilihan A
satu ajah bisanya