2X X3 9 1+ -I X DX X X X DX X DX X X DXỊ Ị Ị Ị• 2 (3 9 2 1) 3 2 9 2...

1.

₂

x x3 9 1+ -I x dx x x x dx x dx x x dx

ị ị ị ị

•

₂

^{(3 9}

²

^{1) 3}

²

⁹

²

¹= = - - = - -+I

₁

=

ị

3x dx

²

=x

³

+ C

₁

⁺I

2

=

ị

x 9x

²

- 1dx ⁼ ₁₈¹

ị

^9x

²

^{- 1 (9d x}

²

^{- 1)=} ₂₇^{1 (9x}

²

^{- 1)}

³

²

^+C

²

⇒ ¹ (9

²

1)

³

²

³

I = 27 x - + x + C

1

2

3

2

2

4

1 xI =

ị

x - x d ^{• Đặt: t = 1- x}

²

^⇒.t

²

^{= -1 x}

²

^{Þ 2tdt = - 2xdx⇒ ( )}