25) (5/4 am³ - ...)² = ... - ... + 9/25 b⁸

The expression is of the form (a-b)², where a=5/4 am³ and b²=9/25 b⁸. Thus, b=3/5 b⁴. (5/4 am³ - 3/5 b⁴)² = (5/4 am³)² - 2(5/4 am³)(3/5 b⁴) + (3/5 b⁴)² = 25/16 a²m⁶ - 3/2 am³b⁴ + 9/25 b⁸. The missing terms are 25/16 a²m⁶ and 3/2 am³b⁴.