Đánh giá mk 5 sao nhé

Bài 1:Tìm x thuộc Q
(x-2)(x+2)(4-x)(x-1)^2,≥0
x ={1;±2;4)(n)
x<-2: x-2<0; x+2<0; 4-x>0;(x-1)^2>0=>A>0(nhan)
-2<x<2=>x-2<0;x+2>0; 4-x>0;(x-1)^2>0=>A>0(l)
2<x<4=>x-2>0;x+2>0; 4-x>0;(x-1)^2>0=>A>0 (nhan)
x>4:=>>x-2>0;x+2>0; 4-x<0;(x-1)^2>0=>A<0(loai)
x€Q; x€(-vc;-2]U[1]U[2;4]

Bài 2
2.
biết B=(x-1)(x+2)(3-x). Tìm x sao cho B<0; <=>(x-1)(x+2)(3-x)<0; x<-2<=>x-1<0;x+2<0;3-x<0=>B>0

-2≤x<1; x-1<0; x+2≥0;;3-x>0=>B≤0(nhan)(loaij x=-2)
1≤x<3; x-1≥0; x+2>0; 3-x>0; =>B≥0(loai)
x≥3; =>x-1>0; x+2>0; 3-x≤0; =>B<0(nhan)losi x=3
x€(-2;1)U(3;vc)