Question

Phân tích đa thức thành nhân tử

a^3+a-30

x^3+x^2+100

Answer 1

\(a^3+a+30\)

\(=a^3+3a^2-3a^2-9a+10a+30\)

\(=\left(a+3\right)\left(a^2-3a+10\right)\)

\(x^3+x^2+100\)

\(=x^3+5x^2-4x^2-20x+20x+100\)

\(=\left(x+5\right)\left(x^2-4x+20\right)\)

Answer 2

`a^3 + a - 30`

`= a^3 + 3a^2 - 3a^2 - 9a + 10a + 30`

`= (a + 3)(a^2 - 3a + 10)`

`--------------------`

`x^3 + x^2 + 100`

`= x^3 + 5x^2 - 4x^2 - 20x + 20x +100`

`= (x+5)(x^3 - 4x + 20)`