Answer: 7m⁴n²
Explanation:
Find the GCF of 21m⁵n² and 28m⁴n².
Find the prime factors of each term in order to find the greatest common factor (GCF).
21m⁵n² = 7 · 3 · m · m · m · m · m · n · n
28m⁴n² = 7 · 2 · 2 · m · m · m · m · n · n
The product of these common prime factors will be the Greatest Common Factor: 7 · m · m · m · m · n · n = 7m⁴n²