Question

Phân tích đa thức sau  thành nhân tử :

a) x^2 - 4x + 3                                                                                              b) x^2 + 5x +4 

c) x^2 - x -6                                                                                                   d) x^4 + 4 

Answer 1

a. x²-4x+3

= x²-x-3x+3

= x(x-1)-3(x-1)

= (x-1)(x-3)

b. x²+5x+4

= x²+x+4x+4

= x(x+1)+4(x+1)

= (x+1)(x+4_

c. x²-x-6

= x²-3x+2x-6

= x(x-3)+2(x-3)

= (x-3)(x+2)

d. x⁴+4

= (x²)²+2²

= (x²)²+4x²+2²-4x²

= (x²+2)²-(2x)²

= (x²+2-2x)(x²+2+2x)

Answer 2

a) \(x^2-4x+3=x^2-x-3x+3=\left(x^2-x\right)-\left(3x-3\right)=x\left(x-1\right)-3\left(x-1\right)=\left(x-1\right)\left(x-3\right)\)b) 

\(x^2+5x+4=x^2+x+4x+4=\left(x^2+x\right)+\left(4x+4\right)=x\left(x+1\right)+4\left(x+1\right)=\left(x+1\right)\left(x+4\right)\)