[tex]5.a) \frac{y+2-(2y-3)}{2y+1}= \frac{y+2-2y+3}{2y+1}= \frac{5-y}{2y+1} \\ \\ \\ b) \frac{4(x+1)+3(2-x)}{12x}= \frac{4x+4+6-3x}{12x}= \frac{x+10}{12x} \\ \\ c)= \frac{(x-4)(x+4)}{2(x+3)}* \frac{(x+3)^{2} }{x+4} = \frac{(x-4)(x+3)}{2} \\ \\ \\ d) \frac{y(y+3)}{y-1}: \frac{(y-3)(y+3)}{(y-1)^{2} } = \\ \\ \frac{y(y+3)}{y-1}* \frac{(y-1) ^{2}}{(y-3)(y+3)}= \\ \\ [/tex]
6.a=( x+4)/(x+2)=(x+2+2)/(x+2)=(x+2)/(x+2)+2)/(x+2)=1+2/(x+2)
a=1+2/(x+2) pentru x=0 se obtine a=1+2/2=1+1=2∈N
pentru x=0⇒a=2∈N
