If A + B = -5 and AB = 6, then find the value of A3 + b3.

If x + y  = n

then, $x^3 + y^3$ = n³ - 3 × n × xy

If A + B = -5 and AB = 6 

Then find the value of A³ + b³

A³ + b³ = -5³ - 3 × -5 × 6 = -125 +  90 = -35