a: \(=\dfrac{-1}{2}\cdot\dfrac{2}{3}\cdot x^2y\cdot xy^2=\dfrac{-1}{3}x^3y^3\)

b: \(=2xy^2\cdot\dfrac{1}{9}x^4y^6=\dfrac{2}{9}x^5y^8\)

a)xy(x²+2y)=xy.x²+xy.2y

                  =x³y+2xy²

b)-4(6x²-xy)=-4.6x²+4.xy

                   =-24x²+4xy

c)4x[x²+6x-1/2]

=4x.x²+4x.6x-4x.1/2

=4x³+24x²-2x

a) \(xy\times\left(x^2+2y\right)=x^3y+2xy^2\)

b) \(-4\times\left(6x^2-xy\right)=-24x^2+4xy\)

c)\(4x\times\left(x^2+6x-\frac{1}{2}\right)=4x^3+24x^2-2x\)

- Rút gọn đơn thức

a) 2x.(x^2 + 3x) - 2 (x^3 - 4 + 3x^2)

\(=2x^3+6x^2-2x^3+8-6x^2\)

\(=\left(2x^3-2x^3\right)+\left(6x^2-6x^2\right)-2x^3+8\)

\(=-2x^3+8\)

b) 2x.(5x + 2) - (10x^2 + 4x + 1)

Cách làm tương tự

a/ \(\left(-2x^2y\right)5xy^4\)

\(=-10x^3y^5\)

tự lm tiếp, rất dễ

a) Ta có: \(\left(-2x^2y\right)\cdot\left(5xy^4\right)\)

\(=\left(-2\cdot5\right)\cdot\left(x^2\cdot x\right)\cdot\left(y\cdot y^4\right)\)

\(=-10x^3y^5\)

b) Ta có: \(\left(\dfrac{27}{10}x^4y^2\right)\cdot\left(\dfrac{5}{9}xy\right)\)

\(=\left(\dfrac{27}{10}\cdot\dfrac{5}{9}\right)\cdot\left(x^4\cdot x\right)\cdot\left(y^2\cdot y\right)\)

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

c) Ta có: \(\left(\dfrac{1}{3}x^3y\right)\cdot\left(-xy\right)^2\)

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

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

11: \(\dfrac{1}{3}x^2y^2\left(6x+\dfrac{2}{3}x^2-y\right)\)

\(=2x^3y^2+\dfrac{2}{9}x^4y^2-\dfrac{1}{3}x^2y^3\)

12: \(\dfrac{3}{4}x^3y^2\left(4x^2y-x+y^5\right)\)

\(=3x^5y^3-\dfrac{3}{4}x^4y^2+\dfrac{3}{4}x^3y^7\)

13: \(-5x^2y^4\left(3x^2y^3-2x^3y^2-xy\right)\)

\(=-15x^4y^7+10x^5y^6+5x^3y^5\)

co sai đè ko bạn

Ko nè bạn ơi

a) Ta có: \(A=1\dfrac{1}{4}\cdot x^3y\cdot\left(-\dfrac{6}{7}xy^5\right)^0\cdot\left(-2\dfrac{2}{3}xy\right)\)

\(=\dfrac{5}{4}x^3y\cdot\dfrac{-8}{3}xy\)

\(=\left(\dfrac{5}{4}\cdot\dfrac{-8}{3}\right)\cdot\left(x^3\cdot x\right)\cdot\left(y\cdot y\right)\)

\(=\dfrac{-10}{3}x^4y^2\)