4)
A(m,0)∈Gf ⇒f(m)=0⇒ [tex] m^{2} +m-2=0\\
m^2+2m-m-2=0\\
m(m+2)-(m+2)=0\\
(m+2)(m-1)=0\\
m+2=0 \\
m=-2\\
m-1=0\\
m=1[/tex]
5)[tex]E(x)=\frac{2x+1}{x+1}+\frac{2x+2-x-1}{(x+1)(x+2)}\cdot\frac{(x+2)(x-2)}{x^2+3x-2x-6}\\
=\frac{2x+1}{x+1}+\frac{x+3}{x+1}\cdot \frac{x-2}{(x+3)(x-2)}=\\
\frac{2x+1}{x+1}+\frac{1}{x+1}=\frac{2x+2}{x+1}=\frac{2(x+1)}{x+1}=2[/tex]
