Question

phân tích đa thức thành nhân tử 
a, x^8 + x^4 +1  
b,x^3 + x^4  -1
d, 15x(x-y) - 25x +25y

Answer 1

  15x( x- y) - 25x + 25y 

= 15x(x-y) - 25 ( x - y)

= (15x - 25) ( x-y)

= 5 (3x - 5)(x-y)

Answer 2

a; x^8 + x^4 + 1 

= x^8 + 2x^4 + 1 - x^4 

= (x^4 + 1) - ( x^2)^2 

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

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

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

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