复数 $z=\frac{1}{2+i}$ (其中 $i$ 为虚数单位) 的虚部为
Finally, the imaginary part of the complex number $z=\frac{1}{2+i}$ is \(\boxed{-\frac{1}{3}}\)
Step 1 :First, we multiply the numerator and denominator by the conjugate of the denominator, which is $2-i$.
Step 2 :\(z = \frac{1}{2+i} \times \frac{2-i}{2-i}\)
Step 3 :\(z = \frac{2-i}{(2+i)(2-i)}\)
Step 4 :\(z = \frac{2-i}{2^2 + i^2}\)
Step 5 :\(z = \frac{2-i}{4 - 1}\)
Step 6 :\(z = \frac{2-i}{3}\)
Step 7 :Finally, the imaginary part of the complex number $z=\frac{1}{2+i}$ is \(\boxed{-\frac{1}{3}}\)