3.
a)5(x-2)/(x-2) · (x-2)²/5=(x-2)²
b)a(3-a)(3+a) : (a+3)/(3-a)a²=
a(3-a)(3+a) · (3-a)a²/(a+3)=a³(3-a)²
c)3/(8-y)(8+y) + (y+8)/(8-y) - 1/(8-y)(8+y)=
Aducem la numitor comun : (8-y)(8+y)
[3+(y+8)²-1]/(8-y)(8+y)=
(2+y²+16y+64)/(8-y)(8+y)=
(y²+16y+66)/(8-y)(8+y)
