What is f(x) = int e^x-e^(-2x) dxf(x)=exe2xdx if f(0)=-2 f(0)=2?

1 Answer
Mar 8, 2018

the antiderivative of f(x) = e^x - e^-(2x) f(x)=exe(2x)

is F(x) = e^x- 1/2e^(2x) + CF(x)=ex12e2x+C

that is to say that the derivative of F(x)F(x) is equal to f(x)f(x)
= d/dx (e^x - e^(2x) / 2 + C) = e^x - e^(-2x) =ddx(exe2x2+C)=exe2x

now we just need to find C to get the total antiderivative of f(x)f(x)
and we can use the fact that at x = 0x=0 the value comes out as -2
therefore f( 0) = -2

therefore
e^0 - e^(2*0) / 2 + C = -2
= 1-1/2 + C = -2

therefore,
C = -2 1/2
=
therefore, the entire function becomes
e^x - e^(2x) / 2 - 2 1/2