Question

Phân tích các đa thức sau thành nhân tử:

\(e,x^2-y^2+6x+9\)

\(f,x^3+3x^2-9x-27\)

Answer 1

\(x^2-y^2+6x+9=\left(x+3\right)^2-y^2=\left(x+3-y\right)\left(x+3+y\right)\)

Answer 2

\(x^3+3x^2-9x-27=x^2\left(x+3\right)-9\left(x+3\right)=\left(x+3\right)\left(x^2-9\right)=\left(x+3\right)^2\left(x-3\right)\)

Answer 3

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

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

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

f) \(x^3+3x^2-9x-27\) \(=(x^3+3x^2)-(9x+27)\)

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

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

\(= (x+3)(x+3)(x-3)\)

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

HỌC TỐT NHA !!!