Question

. Given f(x) = e 2x e 2x + 3e x + 2 : (a) Make the substitution u = e x to convert Z f(x) dx into an integral in u (HINT: The easiest way to do this in Python is to substitute into f(x) u 0 (x) ) (b) Your result from part (a) should be a rational function in u. Find the partial fraction decomposition (directly in Python) and use it to integrate the function. (Remember to substitute x back in when done!) (c) Evaluate Z f(x) dx directly.

Answer 1

Answer:

Step-by-step explanation:

Given;

$f(x)=\frac{e^{2x}}{e^{2x}+3e^x+2}$

a)

substitute $u=e^x\\du=e^x dx\\\\\int\frac{e^{2x}}{e^{2x}+3e^x+2}dx=\int\frac{e^x\dot e^x}{e^x^{2x}+3e^x+2}dx\\\\=\int\frac{udu}{u^2+3u+2}$

b)

Apply partial fraction in (a), we get;

$\frac{u}{u^2+3u+2}=\frac{2}{u+2}-\frac{1}{u+1}\\\\\therefore u^2+3u+2\\=u^2+2u+u+2\\=u(u+2)+1(u+1)\\=(u+2)(u+1)\\\\Now\,\int\frac{u}{u^2+3u+2}\,du=\int\frac{2}{u+2}du-\int\frac{1}{u+1}du\\\\=2ln|u+2|-ln|u+1|+c\\=2ln|e^x+2|-lm|e^x+1|+c$

where C is an arbitrary constant