Question

PTĐTTNT

a/ 9x^2 - x^4 + 2x^3 y - ( xy )^2

b/ x^2 - xy - 8x + 8y

c/ -4xy^2 - y^3 + 25y - 4x^2y

Answer 1

a: \(9x^2-x^4+2x^3y-\left(xy\right)^2\)

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

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

\(=x^2\left[9-\left(x-y\right)^2\right]=x^2\left(3-x+y\right)\left(3+x-y\right)\)

 

b: \(x^2-xy-8x+8y\)

=x(x-y)-8(x-y)

=(x-y)(x-8)

c: \(-4xy^2-y^3+25y-4x^2y\)

\(=y\left(25-4xy-4x^2-y^2\right)\)

\(=y\left[25-\left(4x^2+4xy+y^2\right)\right]\)

\(=y\left[25-\left(2x+y\right)^2\right]=y\left(5-2x-y\right)\left(5+2x+y\right)\)