Let F(x) be the antiderivative of f(x):
F(x)= ∫f(x) dx
F(x) = ∫(10/x2) - (5/x6) dx
F(x) = -10/x +(1/x5) + c
With F(1) =0.
F(1) = 0 = -10/1 +(1/15) + c
0 = -9 + c
c=9
Therefore:
F(x) = -(10/x) +(1/x5) + 9
∴F(3) = -10/3 + 1/35 + 9
F(3) = -10/3 + 1/243 + 9
F(3) = -810/243 + 1/243 + 2187/243
F(3) = 1378/243 ≈ 5.67