The integral ∫e2x−12dx
Let u=e2x
Then dxdu=2e2x=2u
So dx=2udu
∫e2x−12dx=∫u−12⋅2udu
=∫u(u−1)du
u(u−1)1=uA+u−1B
1=A(u−1)+Bu
Put u=0:
1=A(−1)
A=−1
Put u=1:
1=B(1)
B=1
Therefore u(u−1)1=u−1+u−11
∫u(u−1)du=∫u−1du+∫u−11du
=−ln∣u∣+ln∣u−1∣+C
=ln∣u−1∣−ln∣u∣+C
=lnuu−1+C
Substituting u=e2x back:
=lne2xe2x−1+C
Therefore, the integral equals loge2xe2x−1+C