a^3 + 0,064 b^3 = a^3 + (0,4)^3 * b^3 = a^3 + (0,4b)^3 = (a + 0,4b)(a^2 - 0,4ab + (0,4b)^2) = (a + 0,4b)(a^2 - 0,4ab + 0,16b^2)
(0.4m^4-5n)(0.16m^8+2m^4n+25n^2) =0.4m^4 0.16m^8 + 0.4m^4 2m^4n + 0.4m^4 25n^2 - 5n 0.16m^8 - 5n 2m^4n - 5n 25n^2 =0.064m^12 + 0.8m^8n + 10m^4n^2 - 0.8m^8n - 10m^4n^2 - 125n^3 =0.064m^12 + 0.8m^8n - 0.8m^8n - 125n^3 =0.064m^12 - 125n^3.
a^3 + 0,064 b^3 = a^3 + (0,4)^3 * b^3 = a^3 + (0,4b)^3 = (a + 0,4b)(a^2 - 0,4ab + (0,4b)^2) = (a + 0,4b)(a^2 - 0,4ab + 0,16b^2)
(0.4m^4-5n)(0.16m^8+2m^4n+25n^2) =
0.4m^4 0.16m^8 + 0.4m^4 2m^4n + 0.4m^4 25n^2 - 5n 0.16m^8 - 5n 2m^4n - 5n 25n^2 =
0.064m^12 + 0.8m^8n + 10m^4n^2 - 0.8m^8n - 10m^4n^2 - 125n^3 =
0.064m^12 + 0.8m^8n - 0.8m^8n - 125n^3 =
0.064m^12 - 125n^3.