Answer :

3.(4p−2)(p−4)
=(4p+−2)(p+−4)

=(4p)(p)+(4p)(−4)+(−2)(p)+(−2)(−4)

=4p2−16p−2p+8

=4p2−18p+8

Simplified form - 
4p2−18p+8

4.
(2x2+4x−3)(3x+1)

=(2x2+4x+−3)(3x+1)

=(2x2)(3x)+(2x2)(1)+(4x)(3x)+(4x)(1)+(−3)(3x)+(−3)(1)
=6x3+2x2+12x2+4x−9x−3

=6x3+14x2−5x3

Simplified form - 
6x3+14x2−5x3