Answer:
(n - 8n)(m+8n)
Step-by-step explanation:
x² - y² = (x - y)(x + y)
In this situation, the "x" = m and the "y" = 8n
So,
m² - 64n² = (n - 8n)(m+8n)
(m - 8n)(m + 8n)
m² - 64n² ← is a difference of squares and factors in general as
a² - b² = (a - b)(a + b) , then
m² - 64n²
= m² - (8n)²
= (m - 8n)(m + 8n)
