Hitung hasil kalinya a. (3x-5y)(-4x + 7y) b. (-2x+3y)(3x² – 4xy – 5y²) c. (x-2y)(3x + y)(x² – xy – 2y²) -3x²y(x-2y) (3x – y) d.​

SOAL A.

(3x – 5y)•(-4x + 7y)

= (3x)•(-4x) + (3x)•(7y) + (-5x)•(-4y) + (-5y)•(7y)

= -12x² + 21xy + 20xy – 35y²

= -12x² + 41xy – 35y²

= – (12x² – 41xy + 35y²)

SOAL B.

(-2x + 3y)•(3x² – 4xy – 5y²)

= (-2x)•(3x²) + (-2x)•(-4xy) + (-2x)•(-5y²) + (3y)•(3x²) + (3y)•(-4xy) + (3y)•(-5y²)

= -6x³ + 8x²y + 10xy² + 9x²y – 12xy² – 15y³

= -6x³ + 8x²y + 9x²y + 10xy² – 12xy² – 15y³

= -6x³ + 17x²y – 2xy² – 15y³

= – (6x³ – 17x²y + 2xy² + 15y³)

SOAL C.

(x – 2y)•(3x + y)•(x² – xy – 2y²)

= (3x² + xy – 6xy – 2y²)•(x² – xy – 2y²)

= (3x² – 5xy – 2y²)•(x² – xy – 2y²)

= 3x⁴ – 3x³y – 6x²y² – 5x³y + 5x²y² + 10xy³ – 2x²y² + 2xy³ + 4y⁴

= 3x⁴ – 3x³y – 5x³y – 6x²y² + 5x²y² – 2x²y² + 10xy³ + 2xy³ + 4y⁴

= 3x⁴ – 8x³y – 3x²y² + 12xy³ + 4y⁴

SOAL D.

(-3x²y)•(x – 2y)•(3x – y)

= (-3x³y + 6x²y²)•(3x – y)

= (-3x³y)•(3x) + (-3x³y)•(-y) + (6x²y²)•(3x) + (6x²y²)•(-y)

= -9x⁴y + 3x³y² + 18x³y² – 6x²y³

= -9x⁴y + 21x³y² – 6x²y³

= – (9x⁴y – 21x³y² + 6x²y³)