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1) Ta có: \(\dfrac{1}{7}x^2y^3\cdot\left(-\dfrac{14}{3}xy^2\right)\cdot\left(-\dfrac{1}{2}xy\right)\left(x^2y^4\right)\)

\(=\left(-\dfrac{1}{7}\cdot\dfrac{14}{3}\cdot\dfrac{-1}{2}\right)\left(x^2y^3\cdot xy^2\cdot xy\cdot x^2y^4\right)\)

\(=\dfrac{1}{3}x^6y^{10}\)

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

\(=9xy^2\cdot\dfrac{-1}{2}x^3y^2\)

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

3) Ta có: \(\left(-\dfrac{1}{4}x^2y\right)^2\cdot\left(\dfrac{2}{3}xy^4\right)^3\)

\(=\dfrac{1}{16}x^4y^2\cdot\dfrac{8}{27}x^3y^{12}\)

\(=\dfrac{1}{54}x^7y^{14}\)

19 tháng 3 2022

`Answer:`

\( B=-4x^5.y+x^4.y^3-3x^2.y^3.z^2+4.x^5.y-2.y^4-x^4.y-x^4.y+3.y^4+4.y^2.x^2.z^2-y^4+\frac{1}{2}\)

\(=-4x^5y-3x^2y^3z^2+4x^y-2y^4+3y^4+4x^2y^3z^2-y^4+\frac{1}{2}\)

\(=-4x^5y+x^2y^3z^2+4x^y-2y^4+3y^4-y^4+\frac{1}{2}\)

\(=-4x^5y+x^2y^3z^2+4x^y+\frac{1}{2}\)

30 tháng 4 2016

B=-4x^5y+x^4y^3-3x^2y^3z^2+4x^5y-2y^4-x^4y-x^4y+3y^4+4y^2x^2z^2-y^4+\(\frac{1}{2}\)

  =(-4x^5y+4x^5y)+x^4y^3-3x^2y^3z^2+(2y^4+3y^4-y^4)+(-x^4y-x^4y)+4y^2x^2z^2+\(\frac{1}{2}\)

  =x^4y^3-3y^3z^2-2x^4y+4y^2x^2z^2+\(\frac{1}{2}\)

2 tháng 5 2016

ban oi mau tra loi di

29 tháng 6 2023

\(1,\left(x+y\right)^2-\left(x-y\right)^2=\left[\left(x+y\right)-\left(x-y\right)\right]\left[\left(x+y\right)+\left(x-y\right)\right]=\left(x+y-x+y\right)\left(x+y+x-y\right)=2y.2x=4xy\)

\(2,\left(x+y\right)^3-\left(x-y\right)^3-2y^3\)

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

\(=6x^2y\)

\(3,\left(x+y\right)^2-2\left(x+y\right)\left(x-y\right)+\left(x-y\right)^2\\ =\left[\left(x+y\right)-\left(x-y\right)\right]^2\\ =\left(x+y-x+y\right)^2\\ =4y^2\)

\(4,\left(2x+3\right)^2-2\left(2x+3\right)\left(2x+5\right)+\left(2x+5\right)^2\\ =\left[\left(2x+3\right)-\left(2x+5\right)\right]^2\\ =\left(2x+3-2x-5\right)^2\\ =\left(-2\right)^2\\ =4\)

\(5,9^8.2^8-\left(18^4+1\right)\left(18^4-1\right)\\ =18^8-\left[\left(18^4\right)^2-1\right]\\ =18^8-18^8+1\\ =1\)

1: =x^2+2xy+y^2-x^2+2xy-y^2=4xy

2: =x^3+3x^2y+3xy^2+y^3-x^3+3x^2y-3xy^2+y^3-2y^3

=6x^2y

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

4: =(2x+3-2x-5)^2=(-2)^2=4

5: =18^8-18^8+1=1

16 tháng 9 2016

a/ \(x\left(x+4\right)\left(x-4\right)-\left(x^2-1\right)\left(x^2+1\right)=x\left(x^2-16\right)-x^4+1=-x^4+x^3-16x+1\)

b/ \(\left(y-3\right)\left(y+3\right)\left(y^2+9\right)-\left(y^2+2\right)\left(y^2-2\right)=\left(y^2-9\right)\left(y^2+9\right)-y^4+4=y^4-81-y^2+4=-77\)

16 tháng 6 2017

a)\(x\left(x+4\right)\left(x-4\right)-\left(x^2+1\right)\left(x-1\right)\)

\(=x\left(x^2-16\right)-\left(x^2+1\right)\left(x-1\right)\)

\(=x^3-16x-x^3+x^2-x+1\)

\(=x^2-17x+1\)

b)\(\left(y-3\right)\left(y+3\right)\left(y^2+9\right)-\left(y^2+2\right)\left(y^2-2\right)\)

\(=\left(y^2-9\right)\left(y^2+9\right)-\left(y^4-4\right)\)

\(=\left(y^4-81\right)-\left(y^4+4\right)\)

\(=y^4-81-y^4+4=-77\)