Answer: 4x^6-25
Step-by-step explanation:
1. Distribute
(2x^3+5)(2x^3−5)
2(2^3+5)x^3+5(2x^3-5)
2. Distribute
2(2x^3-5)x^3+5(2x^3-5)
4x^6-10x^3+5(2x^3-5)
3. Distribute
4x^6-10x^3+5(2x^3-5)
4x^6-10x^3+10x^3-25
4. Combine like terms
4x^6-10x^3+10x^3-25
4x^6-25