x²(x - 4) +4 (x - 4)
(x² + 4) (x - 4)
First find the common terms that can enter into both x³ and 4x² then write its down in this case it’s x² that can enter x³ leaving only x _since x³/x² = subtract of the indices. x² will also enter 4x² leaving only four hence you having x² (x - 4)
then do the same for the next pair of terms giving you 4 that can enter into both 4 and 16
Leaving you with +4 (x - 4)
Now you can put the common terms together like so (x² + 4) and choose get one of the other two which are the same= (x - 4)
= (x² + 4) (x - 4)