Question

find the value of A and B if Z + 1 and z - 1 are the factor of Z⁴ + az³ +2z²-3z+b

Answer 1

IF Z+1 IS A  FACTOR OF f(z)=z^4+az^3+2z^2-3z+b.
Z+1=0
Z=-1
therefore;
f(-1)=1-a+2+3+b=0
6-a+b=0
a-b=6 eq no. 1
z-1=0
z=1
f(1)=1+a+2-3+b=0
a+b=0 eq no.2

a-b=6
a+b=0
2a=6
a=3

3-b=6
-b=3
b=-3

therefore 
a=3 & b=-3