Answer:
∫ (3x + 1) / (x² + 6x + 8)
Explanation:
The denominator of the first integral factors to:
x⁴ − 1 = (x² − 1) (x² + 1) = (x − 1) (x + 1) (x² + 1)
x² + 1 is not a linear factor, and its roots are not real.
The denominator of the second integral factors to:
x² + 6x + 8 = (x + 2) (x + 4)
These are both linear factors.
The denominator of the third integral is not a linear factor, and its roots are not real.