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| |3x^2+|3-2x| |= 4x^2
<=> 3x^2 + 3-2x=4x^2 ( áp dụng | |a| | = |-a| = |a| = a => ||a|| = a)
<=> 3-2x= 4x^2-3x^2
<=> 3-2x=x^2
<=> x(x+2)=3
<=> x=-3; x=1

ta có:|x-1| 4
=>0|x-1|4
=>|x-1|{0;1;2;3;4}
=>x-10;1;2;3;4;-1;-2;-3;-4}
=>x{1;2;3;4;5;0;-1;-2;-3}
 

bài 1:
a)3xy^3+7xy^2-6xy(6xy=2.3xy)
=3xy(y^2-1)+7xy
=3xy(y^2-1+7/3)
b)3x^2+4xy+y^2-2x-2y
=2(3x^2+4xy+y^2)/2-2(x-y)
=2(3x^2+4xy+y^2)/2-(x-y)
bài 2:
a)4(x+3)^2-(2x+7)(2x-4)=0
<=>4(x^2+2(x+3)+3^2)-4x^2+8x-14x+21=0
<=>4x^2+8x+24+36-4x^2+8x-14x+21=0
<=>2x=24+36+21=81
=>x=81/2
b)x^3+8-4(x^2-4)=0
<=>x^3+8-4x^2+16=0
<=>x^3-4x^2+24=0
<=>x^2(x-4)=-24
                   =4.(-6)
=>x=-2
bài 3: em chịu ;-;