Posted by Amelia on Saturday, November 21, 2009 at 8:26am.
keep getting stuck
for integrate e^(bx) cos x
i get
= cos x e^bx/b  int sin x e^bx/b
= cos x e^bx/b  sin x e^bx/b^2  int  cos x e^bx/b^2
this is where i get stuck please help

Maths  bobpursley, Saturday, November 21, 2009 at 9:05am
Int Udv= uv int vdu
let dv=cosx v=sinx
U=e^bx du=be^bx
int e^bx*cosx=e^bx(sinx)int(bsinx*e^bx
now, to handel the last term, let
dv=sinx v=cosx
u=e^bx du=be^bx
int e^bx coxx=e^bx sinxb[e^bx cosx int(cosx be^bx)
int e^bx cosx=e^bx sinx+be^bx cos x+b^2e^bx cosx
gathering terms,
(1b^2)int e^bx cosx=e^bx(sinx+bcosx)
and you can solve for your original integral underlined. CHECK MY WORK
Answer This Question
Related Questions
 calculus  Differentiate. y= (cos x)^x u= cos x du= sin x dx ln y = ln(cos x)^x...
 Calc.  Differentiate. y= (cos x)^x u= cos x du= sin x dx ln y = ln(cos x)^x ln...
 TRIG!  Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
 calculus  Find complete length of curve r=a sin^3(theta/3). I have gone thus (...
 tigonometry  expres the following as sums and differences of sines or cosines ...
 Mathematics  Trigonometric Identities  Let y represent theta Prove: 1 + 1/tan^...
 algebra  Can someone please help me do this problem? That would be great! ...
 trig  Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
 MATH  Hi, I really need help with these questions. I did some of them halfway, ...
 Math  Solve this equation algebraically: (1sin x)/cos x = cos x/(1+sin x)  ...
More Related Questions