Here,
#I=int_0^1 x^2e^(4x)dx#
#"Using "color(blue)"Integration by Parts:"#
#I=[x^2 ((e^(4x))/4)]_0^1 -int_0^1(2x)((e^(4x))/4)dx#
#I=[1*(e^4/4)-0]-1/2int_0^1xe^(4x)dx#
Again, #"Using "color(blue)"Integration by Parts:"# in second fraction
#I=1/4e^4-1/2[x*((e^(4x))/4)]_0^1 +1/2int_0^1(e^(4x)/4)dx#
#I=1/4e^4-1/2[1*(e^4/4)]+1/8[(e^(4x)/4)]_0^1#
#=1/4e^4-1/8e^4+1/8[e^4/4-e^0/4]#
#=1/4e^4-1/8e^4+1/32e^4-1/32#
#=1/32e^4(8-4+1)-1/32#
#I=5/32e^4-1/32#
#I=1/32(5e^4-1)#