=2a+b-2a+b)/ (2a-b)(2a+b)=2b /4a^2 -b^2
2) =(5*(c^2+c)- (5c-2)(c+3) )/ (c+3)*(c²+c)=
=5c²+5c-(5c²+15c-2c-6) /(c+3)(c²+c)=
=5c²+5c-5c²-15c+2c+6 /(c+3) (c²+c)=-8c+6 /(c+3) (c²+c)
3) =2a(a+5)-5(a-5) -2a² ) /(a-5)(a+5) =2a²+10a-5a+25-2a² / (a-5)(a+5)=
= 5a+25 /(a-5)(a+5) =5(a+5) /(a+5) (a-5) =5/a-5