What is f(x) = int e^(2x)-e^x+x dxf(x)=e2xex+xdx if f(4 ) = 2 f(4)=2?

1 Answer
Jul 4, 2016

f(x)=e^(2x)/2-e^x+x^2/2+e^4-e^8/2-6f(x)=e2x2ex+x22+e4e826

Explanation:

Let I=int(e^(2x)-e^x+x)dx=e^(2x)/2-e^x+x^2/2+CI=(e2xex+x)dx=e2x2ex+x22+C, CC is a constant of integration.

To determine CC, we are given the cond. that f(4)=2f(4)=2.

Now, f(x)=I=e^(2x)/2-e^x+x^2/2+C.f(x)=I=e2x2ex+x22+C. Hence,
f(4)=2 rArr e^8/2-e^4+8+C=2 rArr C=e^4-e^8/2-6. f(4)=2e82e4+8+C=2C=e4e826.

Sub.ing this value of CC in II, we get,

f(x)=e^(2x)/2-e^x+x^2/2+e^4-e^8/2-6f(x)=e2x2ex+x22+e4e826