a: \(\dfrac{x}{x+3}=\dfrac{2}{5}\)
=>5x=2x+6
=>3x=6
hay x=2
b: \(\left(x+\dfrac{1}{2}\right)^2-\dfrac{1}{3}=\dfrac{1}{9}\)
\(\Leftrightarrow\left(x+\dfrac{1}{2}\right)^2=\dfrac{4}{9}\)
=>x+1/2=2/3 hoặc x+1/2=-2/3
=>x=1/6 hoặc x=-7/6
c: \(\left(x-\dfrac{1}{2}\right)^3+\dfrac{1}{4}=\dfrac{3}{8}\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right)^3=\dfrac{3}{8}-\dfrac{2}{8}=\dfrac{1}{8}\)
=>x-1/2=1/2
hay x=1
d: \(2^{x+3}=32\)
=>x+3=5
hay x=2
e: \(\Leftrightarrow3^x\left(3^2+1\right)=90\)
\(\Leftrightarrow3^x=9\)
hay x=2