Question

viết các bt sau thành tích:

a) 8x³-27

b) -x⁴y²-16-8x²y

c) 2xy-x²-y²+16

Answer 1

a , \(8x^3-27=\left(2x\right)^3-3^3=\left(2x-3\right)\left(4x^2+6x+9\right)\)

b , \(-x^4y^2-16-8x^2y=-\left[\left(x^2y\right)^2+4.x^2y+4^2\right]=-\left[x^2y+4\right]^2\)

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

Answer 2

\(a,8x^3-27=\left(2x\right)^3-3^3=\left(2x-3\right)\left(4x^2+6x+9\right)\)\(b,-x^4y^2-16-8x^2y=-\left(x^4y^2+8x^2y+16\right)=-\left(x^2y+4\right)^2\)\(c,2xy-x^2-y^2+16=16-\left(x^2-2xy+y^2\right)=4^2-\left(x-y\right)^2=\left(4-x+y\right)\left(4+x-y\right)\)

Answer 3

a) \(8x^3-27=\left(2x-3\right)\left(4x^2+6x+9\right)\)

b) \(-x^4y^2-16-8x^2y\)

\(=-\left(x^4y^2+8x^2y+16\right)\)

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

c) \(2xy-x^2-y^2+16\)

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

\(=-\left(x-y+4\right)\left(x-y-4\right)\)