a: =>1/3:x=-3/4-2/3=-9/12-8/12=-17/12
=>x=-1/3:17/12=-1/3*12/17=-12/51=-4/17
b: =>5/3x+1/2=1/7
=>5/3x=-5/10
=>x=-5/10:5/3=-5/10*3/5=-3/10
c: =>x+2/5=11/12-2/3=11/12-8/12=3/12=1/4
=>x=1/4-2/5=5/20-8/20=-3/20
g: =>3căn x=5
=>căn x=5/3
=>x=25/9
h: =>-5x=2/5-3/4=8/20-15/20=-13/20
=>x=13/20:5=13/100
k: =>3x-7=0 hoặc x^2-1/4=0
=>\(x\in\left\{\dfrac{7}{3};\dfrac{1}{2};-\dfrac{1}{2}\right\}\)
d) x/(-4) = -9/5
x = (-4).(-9)/5
x = 36/5
e) 2(x - 2/5)³ = -16/27
(x - 2/5)³ = (-16/27) : 2
(x - 2/5)³ = -8/27
x - 2/5 = -2/3
x = -2/3 + 2/5
x = -4/15
f) |x - 2/5| - 0,5 = 1/2
|x - 2/5| = 1/2 + 0,5
|x - 2/5| = 1
x - 2/5 = 1 và x - 2/5 = -1
*) x - 2/5 = 1
x = 1 + 2/5
x = 7/5
*) x - 2/5 = -1
x = -1 + 2/5
x = -3/5
Vậy x = -3/5; x = 7/5
