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Mathematics 6 Online
OpenStudy (luigi0210):

Integration

OpenStudy (luigi0210):

\[\int\limits\frac{ 5dx }{ 2x^2+7x-4 }\]

OpenStudy (jhannybean):

fIRST STEP, TAKEOUT THE 5 FROM THE INTEGRAL caps...

OpenStudy (luigi0210):

Ha, caps

OpenStudy (jhannybean):

\[\large 5 \int\limits \frac{dx}{2x^2+7x-4}\]

OpenStudy (jhannybean):

Ok no this is A REALLY LONG QUESTION.

OpenStudy (jhannybean):

complete the square for the bottom,and double sub.

OpenStudy (luigi0210):

Long questions have never stopped you before :P

OpenStudy (jhannybean):

:( I shall call backup!

OpenStudy (anonymous):

Partial fraction decomposition

OpenStudy (jhannybean):

Mr. Integral is here to integrate your knowledge and power.

OpenStudy (anonymous):

Saw that right away

OpenStudy (luigi0210):

I can show what I got so far

OpenStudy (jhannybean):

Ah. \[\large 2x^2+7x-4\]\[\large x^2+7x-8\]\[\large (x+8)(x-1)\]\[\large(x+4)(2x-1)\]

OpenStudy (jhannybean):

That breaks down into thaaaatt....

OpenStudy (jhannybean):

\[\large 5 \int\limits \frac{1}{(x+4)(2x-1)}= \frac{A}{x+4}+\frac{B}{2x-1}\]

OpenStudy (anonymous):

Leave the 5 inside

OpenStudy (jhannybean):

(i'm just writing what comes to mind)

OpenStudy (luigi0210):

\[\frac{ 5 }{ (2x-1)(x+4) }=\frac{ A }{ 2x-1 }+\frac{ B }{ x+4 }\] \[5=A(x+4)+B(2x-1)\] \[=(A+2B)x+(4A-B)\] \[A=\frac{ 10 }{ 9 }; B=\frac{ -5 }{ 9 }\]

OpenStudy (luigi0210):

skipped a few steps but I think you guys got it

OpenStudy (luigi0210):

where?

OpenStudy (anonymous):

\[\frac{ 10 }{ 9 }\int\limits_{}^{}\frac{ 1 }{ 2x-1 }dx+\int\limits_{}^{}\frac{ 1 }{ x+4 }dx\]

OpenStudy (anonymous):

Woops

OpenStudy (jhannybean):

\[\large \int\limits\limits \frac{5}{(x+4)(2x-1)}= \frac{A}{x+4}+\frac{B}{2x-1}\]\[\large 5=A(2x-1)+B(x+4)\]\[\large 5 = 2Ax-A+Bx+4B\]\[\large 5 = 2x(A+B)+(4B-A)\]

OpenStudy (anonymous):

There's a constant of -5/9 before the 2nd integral

OpenStudy (anonymous):

|dw:1371105793184:dw|

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