If $a+b+c=11$ and $a b+b c+c a=28$, then find the value of $a^3+b^3+c^3-3 a b c$.

407

If $a+b+c=11$

$a b+b c+c a=28$

If the number of equations are less than the number of variables then we can put the extra variables according to our choice = 

So here two equations given and three variables are present so put c = 0

$a+b=11$

$a b=28$

Find the value of $a^3+b^3$ 

$a^3+b^3$  = 11³ - 3 × 11 × 28 = 407