To fully simplify the expression 3k8 × k × 7k5, we can use the properties of exponents and simplify each term separately:
3k8 × k × 7k5
= 3 × k^8 × k × 7 × k^5 (rearranging terms)
= (3 × 7) × (k^8 × k^1) × k^5 (grouping like terms)
= 21k^9 (adding exponents with the same base and multiplying coefficients)
Therefore, the fully simplified expression is 21k^9.