Answer :
rememeber, if ab=0, then assume that a and b=0
assumig yo meant (4k+5)(k+1)=0
set each to zero
4k+5=0
4k=-5
k=-5/4
k+1=0
k=-1
k=-5/4 and/or -1
assumig yo meant (4k+5)(k+1)=0
set each to zero
4k+5=0
4k=-5
k=-5/4
k+1=0
k=-1
k=-5/4 and/or -1