particular antiderivative question?

Question

Determine the particular antiderivative f(x) if the following is true

f'(x)=1-(20/x^3), and f(1)=20

Answer 1

The integral of 1 is X and the integral of -20/X^3 is 10/X^2.

So, the integral of that equation is X+(10/X^2)+C = f(X)

If f(1) = 20, then 20 = 1+(10/1^2)+C 20 = 1+10+C C=9.

So the final answer would be f(X) = X+(10/X^2)+9.

Hopefully this makes sense...

Answer 2

Int = x +10/x^2 +C
I suppose the antiderivative at 1 must be 20
1+10+c=20 so C= 9
and F(x) = x +10/x^2+9