1. а) (35а^6b^3)/(21a^2b^4)=(5/3)*a^4*b^-1=(5a^4)/(3b)
б) (15x^2)/(6x+15x^2)=(15x^2)/(3x*(2+5x))=(5x)/(2+5x)
в) (x-3)(x+3)/(x+3)=x-3
2. а) (7y+4)/(8y)-(2y+3)/(6y)=(21y+12-8y-12)/(24y)=13y/24y=13/24
б) a/(a+4)+a/(a-4)=(a^2-4a+a^2+4a)/(a^2-16)=(2a^2)/(a^2-16)
3. (x-10y^3)/(2y)+5y^2=(x-10x^3+10x^3)/2y=x/2y
при х=-18, у=4,5
-18/9=-2
4. 1+(2a-1)/((a-1)^2)-a/(a-1)=(a^2-2a+1-2a-1-a^2+a)/((a-1)^2)=-3a/((a-1)^2)