Question

Factorise 125a3+b3+64c3-60abc

Answer 1

(5a)^3 + (b)^3 + (4c)^3 - 3×5a×b×4c
(5a+b+4c)(25a^2+b^2+16c^2-5ab-4bc-20ac)

Answer 2

a^3 + b^3 +c^3 -3abc = (a+b+c)(a sq + b sq + c sq -ab-bc-ca)
Here a=5a
b=b
c=4c
On substitution:
=(5a+b+4c)(25a^2 + b ^2 + 16c^2 -5ab-4bc-20ac)