E(x)=(x²-9)/(x+1)²-4
a) cond.x²+2x+1-4≠0⇒x²+2x-3≠0
(x-1)(x+3)≠0
x1≠1
x2≠-3
x²-9=0
x²=9
x²=√9
x1=3
x2=-3
x∈{-3,3}
b) E(2)=(2²-9)/(2+1)²-4=(4-9)/(9-4)=-5/5=-1
E(-1)=((-1²-9)/(-1+1)²-4=-8/-4=2
E(2)+E(-1)=-1+2=1
c) E(x)=(x+3)(x-3)/(x-1)(x+3)=x-3/x-1
d) E(x)=x-3/x+1
cond.x≠-1
x-3=0
x=3