rubilovalex 1). a^2+2ab+b^2/a^2-b^2=(a+b)^2/(a+b)(a-b)=(a+b)/(a-b); 2). x^2-2x+1/x^2-1=(x-1)^2/(x-1)(x+1)=(x-1)/(x+1); 3). 3a^2-6ab+3b^2/6a^2-6b^2=3(a^2-2ab+b^2)/6(a^2-b^2)=3(a-b)^2 /6(a-b)(a+b)=(a-b)/2(a+b); 4).5m^2+10mn+5n^2/15m^2-15n^2=5(m^2+2mn+n^2)/15(m^2-n^2)=5(m+n)^2/15(m+n)(m-n)=(m+n)/3(m-n).