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SOAL A.

(2a – b)³

= (2a – b)•(2a – b)•(2a – b)

= (4a² – 2ab – 2ab + b²)•(2a – b)

= (4a² – 4ab + b²)•(2a – b)

= (8a³ – 4a²b – 8a²b + 4ab² + 2ab² – b³)

= (8a³ – 12a²b + 6ab² – b³)

SOAL B.

(2x + y – 3)²

= (2x + y – 3)•(2x + y – 3)

= (4x² + 2xy – 6x + 2xy + y² – 3y – 6x – 3y + 9)

= (4x² – 6x – 6x + 2xy + 2xy – 3y – 3y + y² + 9)

= (4x² – 12x + 4xy – 6y + y² + 9)

SOAL C.

(a + b)²•(4a – b + 2)

= (a + b)•(a + b)•(4a – b + 2)

= (a² + ab + ab + b²)•(4a – b + 2)

= (a² + 2ab + b²)•(4a – b + 2)

= (4a³ – a²b + 2a² + 8a²b – 2ab² + 4ab + 4ab² – b³ + 2b²)

= (4a³ + 2a² – a²b + 8a²b + 4ab – 2ab² + 4ab² + 2b² – b³)

= (4a³ + 2a² + 7a²b + 4ab + 2ab² + 2b² – b³)

SOAL D.

(x + y + 5)•(3x – 2y)

= (3x² – 2xy + 3xy – 2y² + 15x – 10y)

= (3x² + 15x – 2xy + 3xy – 10y – 2y²)

= (3x² + 15x + xy – 10y – 2y²)