7:
a: A(x)=0
=>2/3x-5/9=0
=>2/3x=5/9
=>x=5/9:2/3=5/9*3/2=15/18=5/6
b: B(x)=0
=>x^2-4/25=0
=>x^2=4/25
=>x=2/5 hoặc x=-2/5
c: C(x)=0
=>1/2x^3+4/27=0
=>1/2x^3=-4/27
=>x^3=-8/27
=>x=-2/3
d: D(x)=0
=>x(x^2-1/8)=0
=>x=0 hoặc \(x=\pm\dfrac{\sqrt{2}}{4}\)
e: E(x)=0
=>x^4-16/81=0
=>x^4=16/81
=>x=2/3 hoặc x=-2/3
f: F(x)=0
=>x(2x-3)(1-x^3)=0
=>x=0;x=3/2;x=1
i: I(x)=0
=>2(2-x)+1/2(x-2)^2=0
=>(x-2)(-2+1/2x-1)=0
=>(x-2)(1/2x-3)=0
=>x=6 hoặc x=2
g: g(x)=0
=>x^97(x^3-8)=0
=>x=0 hoặc x=2










