Rút gọn biểu thức: (3x^2-5xy- 4y^2) . ( 2x^2+ y^2) + ( 2x^4y- x^3y^3- x^2y^4) :( 1/5xy) .

Trả lời

$\left(3x^2-5xy-4y^2\right).\left(2x^2+y^2\right)+\left(2x^{4}y-x^3{y}^3-x^2{y}^4\right):\left(\frac{1}{5}xy\right)$

= 6x⁴ – 10x³y – 8x²y² + 3x²y² – 5xy³ – 4y⁴ + 10x³ – 5x²y² – 5xy³

= 6x⁴ – 10x³y + (3x²y² – 8x²y² – 5x²y²) – (5xy³ + 5xy³) – 4y⁴ + 10x³

= 6x⁴ – 10x³y + (3x²y² – 8x²y² – 5x²y²) – (5xy³ + 5xy³) – 4y⁴ + 10x³

= 6x⁴ – 10x³y – 10x²y² – 10xy³ – 4y⁴ + 10x³.