1.
1)5+a/2a^2+1-2a/a=5+a+2a(1-2a)/2a^2=5+a+2a-4a^2=5+3a-4a^2/2a^2
2)4x+8/12x^3*3x/x+2=4(x+2)/4x^2*1/x+2=1/x^2
3)(m+n)^2:m^2-n^2/8m=(m+n)^2*8m/m^2-n^2=(m+n)^2*8m/(m-n)(m+n)=(m+n)*8m/m-n=8m^2+8mn/m-n
4)2-b/b-b-3/3b^2=3b(2-b)-(b-3)/3b^2=6b-3b^2-b+3/3b^2=5b-3b^2+3/3b^2