Question

Làm tính nhân :

a) \(3x\left(5x^2-2x-1\right)\)

b) \(\left(x^2+2xy-3\right)\left(-xy\right)\)

c) \(\dfrac{1}{2}x^2y\left(2x^3-\dfrac{2}{5}xy^2-1\right)\)

Answer 1

a,3x(5x^2-2x-1)

=15x^3-6x^2-3x

Answer 2

a) \(3x\left(5x^2-2x-1\right)\)

\(=15x^3-6x^2-3x\)

b) \(\left(x^2+2xy-3\right)\left(-xy\right)\)

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

c) \(\dfrac{1}{2}x^2y\left(2x^3-\dfrac{2}{5}xy^2-1\right)\)

\(=x^5y-\dfrac{1}{5}x^3y^3-\dfrac{1}{2}x^2y\)

Answer 3

a) 3x(5x²-2x-1) = 15x³ - 6x² - 3x

b) (x²+2xy-3)(-xy) = -x³y - 2x²y² + 3xy

c) \(\dfrac{1}{2}\)x²y\((\)2x³ - \(\dfrac{2}{5}\)xy² - 1) = x⁵y - \(\dfrac{1}{5}\)x³y³ - \(\dfrac{1}{2}\)x²y

Answer 4

a) 3x (5x²-2x-1)

=15x³-6x²-3x

b) (x²-2xy-3)(-xy)

=-x³y+2x²y²+3xy

c) 1/2x²y(2x³-2/5xy²-1)

=x⁵y-1/5x³y³-1/2x²y

Answer 5

a. 3x(5x² - 2x -1) = 15x³ - 6x² - 3x

b. (x²+2xy -3)(-xy) = - x³y – 2x²y² + 3xy

c. \(\dfrac{1}{2}\)x²y ( 2x³- \(\dfrac{2}{5}\)xy²-1 )= x⁵y -\(\dfrac{1}{5}\)x³y³- \(\dfrac{1}{2}\)x2y