E(x)=[tex] \frac{(x+2)^{2}-9 }{x^{2} -25} [/tex] : [tex] \frac{x-1}{x-5} [/tex] cu x≠+-5 si x≠1
folosim formula a²-b²=(a-b)·(a+b) de descompunere in factori
x²-25=x²-5²=(x-5)·(x+5) (x+2)²-9=(x+2)²-3²=(x+2-3)·(x+2+3)=(x-1)·(x+5)
a=x a=x+2
b=5 b=3
E(x)=[tex] \frac{(x-1)(x+5)}{(x-5)(x+5)} [/tex]·[tex] \frac{(x-5)}{(x-1)} [/tex]=1
