Odpowiedź :
(2x-y)³ + (y-3)² -(y-3x)(y+3x)=
8x³ + y² - 9 - y² + 3xy - 3xy - 9x² =
8x³ - 9 - 9x²
8x³ + y² - 9 - y² + 3xy - 3xy - 9x² =
8x³ - 9 - 9x²
musimy skorzystać ze wzorów
(a-b)³ = a³ - 3a²b + 3ab² - b³
(a-b)² = a² - 2ab + b²
(a-b)(a+b)= a²-b²
(2x-y)³ + (y-3)² -(y-3x)(y+3x)=
=8x³-12x²y+6xy²-y³+y²-6y+9-y²+9x²=
=8x³-12x²y+6xy²-y³-6y+9+9x²
(a-b)³ = a³ - 3a²b + 3ab² - b³
(a-b)² = a² - 2ab + b²
(a-b)(a+b)= a²-b²
(2x-y)³ + (y-3)² -(y-3x)(y+3x)=
=8x³-12x²y+6xy²-y³+y²-6y+9-y²+9x²=
=8x³-12x²y+6xy²-y³-6y+9+9x²