Đáp án:
Giải thích các bước giải:
b) ( x+ 1/2) .( 2/3-2x)
= 2/3x + 1/3 -2x^2 - x
= -2x^2 -1/3 x +1/3
c ) ( x+ 1/50 )^2 +17/25= 26/25
<-> (x+ 1/50 ) ^2 = 9/25
<-> (x+1/50)^2 = ( 3/5)^2
<-> x+1/50=3/5 or x+1/50=-3/5
<-> x= 29/50 or x= -31/50
d ) 25/4 x -11/2 x = 25%
<-> 3/4 x = 0,25
<-> x = 1/3
f ) (1/2 +3/4-1/2) : -5/6 <x < 4/21 : 4/-7
<-> 3/4 : -5/6 <x < -1/3
<-> -9/10<x< -1/3