Question

Bài 1: phân tích đa thức thành nhân tử a, X³+7x²+15x+9 b, X³-3x²+4 c, X³+2x²+3x+2 d, X³+6x²+11x+6

Answer 1

a)

A=(x^3+3x^2+3x+1)+4(x^2+2x+1)+7(x+1)

A=(x+1)^3+4(x+1)^2+7(x+1)

A=(x+1)[(x+1)^2+4(x+1)+7)]

b)

B=x^3-3x^2+4

=(x^3+x^2)-4(x^2-1)

B=(x+1)[x^2-4(x-1)]

=(x+1)[x^2-4x+4)

=(x+1)(x-2)^2

Answer 2

c)

c=(x^3+3x^2+3x+1)-(x^2-1)

=(x+1)^3-(x-1)(x+1)[

=(x+1)[(x+1)^2-(x-1)]

C=(x+1)[(x^2+x+2)

d)

D=(x^3+x^2)+(5x^2+5x)+(6x+6)

D=(x+1)[x^2+5x+6]

D=(x+1)(x+2)(x+3)