Integral (x akar (9-x^2)) dx =

integral

∫ (x √(9-x²) dx

substitusi

u = 9 - x²

du = -2x dx

x dx = - 1/2 du

∫ (x √(9-x²) dx = ∫ -1/2 √u du

= - 1/2 ∫ u^(1/2) du

= - 1/2 . (2/3) (u) ^(3/2) + c

= - 1/3 u √ u + c

atau

= - 1/3 (9 - x²) √(9 - x²) + c