a) 4.(1/2 - 3) - 6. ( 5/6x +2 ) = 0
<=> 2-12-5/x-12=0;
<=> -10-5/x-12=0;
<=> -5/x=22;
x=-5/22;
.
b) 3x^2 - 2x = 0
x(3x-2)=0;
<=> x=0 hoặc 3x-2 = 0;
<=> x=0 hoặc x=2/3;
.
c) ( x - 2^3) + 8/27 = 0
<=> x-8+8/27=0;
<=>x=208/27;
.
d) 4 .1/3 : x/4 = 6 : 0,3
4/3: x/4 =20;
<=> x/4=1/15;
x=4/15;
.
e) ( 0,25 - 30% x ) . 1/3 - 1/4 = 5. 1/6
<=> 1/12-x/10-1/4=5/6
<=> x/10=-1;
<=> x=-10