How would you go about integrating a function which has an exponential and a cos/sin term?

For this type of integral you would need to use integration by parts twice. Remember this is where the integral of u*(dv/dx)=uv-(integral with respect to x)(v*(du/dx)). For example let's say you need to integrate sin(x)e^x, it doesn't matter which you choose to be u and dv/dx as sin(x) is cyclic and e^x doesn;t change under differnetiation/integration. And so arbitarily say u=sin(x) and dv/dx=e^x therefore du/dx=cos(x) and v=e^x. We will call the original integral I and so now we have I=sin(x)e^x-(integral with respect to x)(cos(x)e^x). then perform it again but with different variables. Now we change u=cos(x) and dv/dx=e^x, it can be usefull to use subscripts to not confuse u and v from what they previously were, therefore du/dx=-sin(x), v=e^x. From this we have I=sin(x)e^x-cos(x)e^x-(integral with respect to x)(sin(x)e^x)+c, and the integral left now is the same as the original and so equals I, hence this can be reaaranged to 2I=sin(x)e^x-cos(x)e^x+c. This can be cleaned up to get I=((sin(x)-cos(x))e^x)/2+c, is this all clear?

LR
Answered by Luke R. Maths tutor

4200 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

A level Maths question - The graph of y=2sin(2x)+1 is rotated 360 degrees about the x-axis to form a solid. Find the volume enclosed by the curve, the co-ordinate axes and the line x=pi/2


f(x)=(2x+1)/(x-1) with domain x>3. (a)Find the inverse of f(x). (b)Find the range of f(x). (c) g(x)=x+5 for all x. Find the value of x such that fg(x)=3.


I don't understand how to visualise differentiation, please could you show my an example to allow me to understand what it actually is better?


express (1+4(root7)) / (5+2(root7)) as a+b(root7), where a and b are integers


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning