The signal to quantization noise ratio in an n-bit PCM system

For a narrow band noise with Gaussian quadrature and inphase components, the probability density function of its enveolope will be

If $$L\left(f\left(t\right)\right)=\frac{2\left(s+1\right)}{s^2+2s+5}$$ then f(0⁺) and f($$\infty$$) are given by [Note: 'L' stands for 'Laplace Transform of']

The step error coefficient of a system G(s)=$$\frac1{\left(s+6\right)\left(s+1\right)}$$ with unity feedback is