What am I doing wrong?
http://img26.imageshack.us/img26/8339/algebra474.png
What am I doing wrong?
http://img26.imageshack.us/img26/8339/algebra474.png
That exercise doesn't have it's solution on the book, so could you please tell me if I did it right?
http://img690.imageshack.us/img690/8339/algebra474.png
$\displaystyle \frac{a(a+1)}{3a(a-1)(a+1)} + \frac{3(a-1)(a+2)}{3a(a-1)(a+1)} - \frac{2a(2a-1)}{3a(a-1)(a+1)}$$\displaystyle =\frac{a(a+1)+3(a-1)(a+2)-2a(2a-1)}{3a(a-1)(a+1)}$ $\displaystyle = \frac{6(a-1)}{3a(a^{2}-1)}$ $\displaystyle = \frac{2(a-1)}{a(a^{2}-1)}$.