Question

Thực hiện các phép tính:

a) (9x²y³ - 12x⁴y⁴) : 3x²y - (2 - 3x²y)y².

b) [5(x+ 2y²)(x - 2y²) - \(\frac{2}{5}\)(5x - 4y²)(x + 12,5y²)] : (-0,3x).

Answer 1

a) Ta có: \(\left(9x^2y^3-12x^4y^4\right):3x^2y-\left(2-3x^2y\right)\cdot y^2\)

\(=3y^2-4x^2y^3-2y^2+3x^2y^3\)

\(=y^2-x^2y^3\)

b) Ta có: \(\left[5\left(x+2y^2\right)\left(x-2y^2\right)-\left(5x-4y^2\right)\left(x+12.5y^2\right)\right]:\left(-0.3x\right)\)

\(=\left[5\left(x^2-4y^4\right)-\left(5x^2+62.5xy^2-4xy^2-50y^4\right)\right]:\left(-0.3x\right)\)

\(=\left(5x^2-20y^4-5x^2-58.5xy^2+50y^4\right):\left(-0.3x\right)\)

\(=\left(30y^4-58.5xy^2\right):\left(-0.3x\right)\)

\(=\frac{-0.3\cdot\left(-100y^4+195xy^2\right)}{-0.3x}=\frac{-100y^4+195xy^2}{x}\)