Question

If a directly proportion to b and b directly proportion to c prove that a^3+b^3+c^3 directly proportion 3abc.

Answer 1

given a,b,c are directly proportional to each other
it comes they are equal case
a=b=c
then
${a}^{3} + {b}^{3} + {c}^{3} = 3abc$
in all other cases
it is directly proportional to each other
the above formulae is when a,b,c are equal
(refer polynomial equations)