Answer:
the GCF is 3x^3
Explanation:
Identifying the greatest common factor of an expression like this one involves finding the GCF of each term when the terms are placed side by side: the GCF of -15x^3 and 6x^4 is 3x^3, because 3 and x^3 are the largest factors of their type (constant, power of x) that will divide evenly into -15x^3 and 6x^4.
The end result is 3x^3(-5, 2x). Once again, the GCF is 3x^3.