Problem: The expression a3−a−3 equals:
Answer Choices:
A. (a−a1​)(a2+1+a21​)
B. (a1​−a)(a2−1+a21​)
C. (a−a1​)(a2−2+a21​)
D. (a1​−a)(a21​+1+a2)
E. (none of these)
Solution:
a3−a−3=a3−a31​=(a−a1​)(a2+1+a21​).