x²-4=8(x-2)
=> x²-4=8x-16
=> x²-8x+16-4=0
=> (x-4)²-4=0
=>(x-4-2)(x-4+2)=0
=> (x-2)(x-6)=0
=> x-2=0 nên x=2
x-6 =0 nên x=6
a) x^2 - 4 = 8(x - 2)
<=> (x - 2)(x + 2) - 8(x - 2) = 0
<=> (x - 2)(x+2-8)=0
<=>(x-2)(x-6)=0
<=>x-2=0 hoặc x-6=0
<=>x=2 hoặc x=6
Vậy S={2;6}
b)x^2-4x+4=9(x-2)
<=>(x-2)^2-9(x-2)=0
<=>(x-2)(x-2-9)=0
<=>(x-2)(x-11)=0
<=>x-2=0 hoặc x-11=0
<=>x=2 hoặc x=11
Vậy S={2;11}
c)4x^2-12x+9=(5-x)^2
<=>(2x)^2-2.2x.3+3^2=(5-x)^2
<=>(2x-3)^2-(5-x)^2=0
<=>(2x-3-5+x)(2x-3+5-x)=0
<=>(3x-8)(x+2)=0
<=>3x-8=0 hoặc x+2=0
<=>3x=8 hoặc x= - 2
<=>x=8:3(8 phần 3) hoặc x= -2
Vậy S={8:3 ; -2}
B , x^2 - 4x +4 = 9 ( x-2)
=> (x-2)^2 -9(x-2) = 0
=> (x-2-9)(x-2) = 0
=>( x-11 ) ( x-2)=0
=> x= 11
x=2
C, 4x^2 - 12x+9 =(5-x)^2
=>( 2x-3)^2 = (5-x)^2
=> (2x-3-5+x ) (2x-3+5-x ) = 0
=> 3x-8) ( x-2 ) =0
=> x= 8/3
x = -2
