Simplify: (x−3y−5z)(x2+9y2+25z2+3xy−15yz+5zx)
⇒x3+xy2(9−9)+xz2(25−25)+x2y(3−3)−15xyz−15xzy−15xyz
+zx2(5−5)−27y3+yz2(−75+75)−125z3+y2z(45−45)
Factorise each of the following: 27y3+125z3 [ 3 MARKS]