Integration
\[\int\limits\frac{ 5dx }{ 2x^2+7x-4 }\]
fIRST STEP, TAKEOUT THE 5 FROM THE INTEGRAL caps...
Ha, caps
\[\large 5 \int\limits \frac{dx}{2x^2+7x-4}\]
Ok no this is A REALLY LONG QUESTION.
complete the square for the bottom,and double sub.
Long questions have never stopped you before :P
:( I shall call backup!
Partial fraction decomposition
Mr. Integral is here to integrate your knowledge and power.
Saw that right away
I can show what I got so far
Ah. \[\large 2x^2+7x-4\]\[\large x^2+7x-8\]\[\large (x+8)(x-1)\]\[\large(x+4)(2x-1)\]
That breaks down into thaaaatt....
\[\large 5 \int\limits \frac{1}{(x+4)(2x-1)}= \frac{A}{x+4}+\frac{B}{2x-1}\]
Leave the 5 inside
(i'm just writing what comes to mind)
\[\frac{ 5 }{ (2x-1)(x+4) }=\frac{ A }{ 2x-1 }+\frac{ B }{ x+4 }\] \[5=A(x+4)+B(2x-1)\] \[=(A+2B)x+(4A-B)\] \[A=\frac{ 10 }{ 9 }; B=\frac{ -5 }{ 9 }\]
skipped a few steps but I think you guys got it
where?
\[\frac{ 10 }{ 9 }\int\limits_{}^{}\frac{ 1 }{ 2x-1 }dx+\int\limits_{}^{}\frac{ 1 }{ x+4 }dx\]
Woops
\[\large \int\limits\limits \frac{5}{(x+4)(2x-1)}= \frac{A}{x+4}+\frac{B}{2x-1}\]\[\large 5=A(2x-1)+B(x+4)\]\[\large 5 = 2Ax-A+Bx+4B\]\[\large 5 = 2x(A+B)+(4B-A)\]
There's a constant of -5/9 before the 2nd integral
|dw:1371105793184:dw|
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