356. Calculate the integral $\int_{0}^{5} \frac{d x}{\sqrt{x+4}}$ using the trapezoidal rule, dividing the interval of integration into 5 equal parts.
Solution. Here $n=5 ; \Delta x=1 ; x_{0}=0 ; x_{1}=1 ; x_{2}=2 ; x_{3}=3 ; x_{4}=4$; $x_{5}=5$. Next, we find $y_{0}=\frac{1}{\sqrt{4}}=\frac{1}{2} ; y_{1}=\frac{1}{\sqrt{1+4}} \approx 0.447 ; y_{2}=\frac{1}{\sqrt{2+4}} \approx$ $\approx 0.409 ; y_{3}=\frac{1}{\sqrt{3+4}} \approx 0.377 ; y_{4}=\frac{1}{\sqrt{4+4}} \approx 0.353 ; y_{5}=\frac{1}{\sqrt{5+4}}=\frac{1}{3}$.

Using formula (12) we get

$$
\int_{0}^{5} \frac{d x}{\sqrt{x+4}} \approx 1(0.416+0.447+0.409+0.377+0.353)=2.002
$$