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19 tháng 7 2016

a)\(x^4+64=x^4+16x^2+64-16x^2\)

\(=\left(x^2\right)^2+2.x^2.8+8^2-\left(4x\right)^2\)

\(=\left(x^2+8\right)^2-\left(4x\right)^2\)

\(=\left(x^2+8-4x\right)\left(x^2+8+4x\right)\)

b)\(4x^4+81=4x^4+36x^2+81-36x^2\)

\(=\left(2x^2\right)^2+2.2x^2.9+9^2-\left(6x\right)^2\)

\(=\left(2x^2+9\right)^2-\left(6x\right)^2\)

\(=\left(2x^2+9-6x\right)\left(2x^2+9+6x\right)\)

c)\(x^4y^4+64=x^4y^4+16\left(xy\right)^2+64-16\left(xy\right)^2\)

\(=\left[\left(xy\right)^2\right]^2+2.\left(xy\right)^2.8+8^2-\left(8xy\right)^2\)

\(=\left[\left(xy\right)^2+8\right]^2-\left(8xy\right)^2\)

\(=\left[\left(xy\right)^2+8-8xy\right]\left[\left(xy\right)^2+8+8xy\right]\)

11 tháng 7 2016

a) \(x^2\left(x-3\right)+12-4x=x^2\left(x-3\right)-4x+12\)

\(=x^2\left(x-3\right)-4\left(x-3\right)\)

\(=\left(x-3\right)\left(x^2-4\right)\)

\(=\left(x-3\right)\left(x^2-2^2\right)\)

\(=\left(x+3\right)\left(x-2\right)\left(x+2\right)\)

b)\(x^2-4+\left(x-2\right)^2=x^2-2^2+\left(x-2\right)^2\)

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

\(=\left(x-2\right)\left(x+2+x-2\right)\)

\(=\left(x-2\right)2x\)

c)\(x^3-4x^2-12x+27=x^3+3x^2-7x^2-21x+9x+27\)

\(=x^2\left(x+3\right)-7x\left(x+3\right)+9\left(x+3\right)\)

\(=\left(x+3\right)\left(x^2-7x+9\right)\)

\(=\left(x+3\right)\left(x^2-7x+9\right)\)

11 tháng 7 2016

a) => x2.(x-3)-4(x-3)=(x-3)(x2-4)=(x-3)(x-2)(x+2)

b) => (x+2)(x-2)+(x-2)2=(x-2)(x+2+x-2)=2x(x-2)

c) => x3+27-(4x2+12x)=(x+3)(x2-3x+3)-4x(x+3)=(x+3)(x2-3x+3-4x)=(x-3)(x2-7x+3)

25 tháng 4 2019

10 tháng 7 2016

1) \(25-x^2-y^2+2xy=5^2-\left(x^2-2xy+y^2\right)=5^2-\left(x-y\right)^2\)\(=\left(5-x+y\right)\left(5+x-y\right)\)

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

10 tháng 7 2016

1) \(25-x^2-y^2+2xy\)

\(=5^2-\left(x^2+y^2-2xy\right)\)

\(=5^2-\left(x-y\right)^2\)

\(=\left(x-y-5\right)\left(x-y+5\right)\)

2) \(3x-3y-x^2+2xy-y^2\)

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

\(=3\left(x-y\right)-\left(x-y\right)\left(x-y\right)\)

\(=\left(3-x+y\right)\left(x-y\right)\)