Answer:
(2d + d³) / (1 + d²)
Step-by-step explanation:
1 / ((1/d) + d) + d
Multiply top and bottom of the fraction by d:
d / (1 + d²) + d
Use common denominator to add.
d / (1 + d²) + d (1 + d²) / (1 + d²)
(d + d (1 + d²)) / (1 + d²)
(d + d + d³) / (1 + d²)
(2d + d³) / (1 + d²)
