- #1
nameVoid
- 241
- 0
[tex]
\int \frac{5x^2+11x+17}{x^3+5x^2+4x+20}dx
[/tex]
[tex]
\int \frac{5x^2+11x+17}{(x^2+4)(x+5)}dx
[/tex]
[tex]
\frac{Ax+B}{x^2+4}+\frac{C}{x+5}=\frac{5x^2+11x+17}{(x^2+4)(x+5)}
[/tex]
[tex]
(Ax+B)(x+5)+C(x^2+4)=5x^2+11x+17
[/tex]
[tex]
Ax^2+5Ax+Bx+5B+Cx^2+4C=5x^2+11x+17
[/tex]
[tex]
x^2(A+C)+x(5A+B)+(5B+4C)=5x^2+11x+17
[/tex]
[tex]
A+C=5, 5A+B=11, 5B+4C=17
[/tex]
[tex]
A=5-C
[/tex]
[tex]
5(5-C)+B=11, 25-5C+B=11, B=-14+5C
[/tex]
[tex]
5(-14+5C)+4C=17, -70+29C=17, C=3, B=1, A=2
[/tex]
[tex]
\int \frac{2x+1}{x^2+4}+ \frac{3}{x+5}dx
[/tex]
[tex]
ln(x^2+4) +aractan(x/2)/2+3ln|x+5|+Z
[/tex]
orginally I thought I had made a mistake somwhere but I believe this is correct please make suggestions I am new to this technique
\int \frac{5x^2+11x+17}{x^3+5x^2+4x+20}dx
[/tex]
[tex]
\int \frac{5x^2+11x+17}{(x^2+4)(x+5)}dx
[/tex]
[tex]
\frac{Ax+B}{x^2+4}+\frac{C}{x+5}=\frac{5x^2+11x+17}{(x^2+4)(x+5)}
[/tex]
[tex]
(Ax+B)(x+5)+C(x^2+4)=5x^2+11x+17
[/tex]
[tex]
Ax^2+5Ax+Bx+5B+Cx^2+4C=5x^2+11x+17
[/tex]
[tex]
x^2(A+C)+x(5A+B)+(5B+4C)=5x^2+11x+17
[/tex]
[tex]
A+C=5, 5A+B=11, 5B+4C=17
[/tex]
[tex]
A=5-C
[/tex]
[tex]
5(5-C)+B=11, 25-5C+B=11, B=-14+5C
[/tex]
[tex]
5(-14+5C)+4C=17, -70+29C=17, C=3, B=1, A=2
[/tex]
[tex]
\int \frac{2x+1}{x^2+4}+ \frac{3}{x+5}dx
[/tex]
[tex]
ln(x^2+4) +aractan(x/2)/2+3ln|x+5|+Z
[/tex]
orginally I thought I had made a mistake somwhere but I believe this is correct please make suggestions I am new to this technique