3.
a. x^2-xy+x-y = (x^2+x)-(xy+y)
b. 5x^3-10x^2y+5xy^2 = 5x(x^2-2xy+y) [nếu y^3 thì phân tích tiếp]
= x(x+1)-y(x+1)
= (x-y)(x+1)
4. 5x(x-1)-x+1=0
=> 5x(x-1)-(x-1)=0
=>(5x-1)(x-1)=0 (2 TH)
TH1: 5x-1=0 TH2: x-1=0
=>5x=1 =>x=1
=>x=0,2(hoặc 1/5)
vậy x={0,2 ; 1}
6.
a. 5x^2y-10xy^2 = 5xy(x-2y)
b. 3(x+3)-x^2+9 = 3(x+3)-(x^2-3^2)
= 3(x+3)-(x-3)(x+3)
= (x+3)[3-(x-3)]
= (x+3)x
c. ko có
d. x^2+4x = x(x+4)
e. x^3-2x^2+5x-10 = x^2(x-2)+5(x-2)
= (x^2+5)(x-2)
