\(a,=\dfrac{12x+3-6x-4}{6}=\dfrac{6x-1}{6}\\ b,=\dfrac{x^2-9-x^2+9}{x\left(x-3\right)}=0\\ c,=\dfrac{x^2+3x-x+1}{x\left(x-1\right)\left(x+1\right)}=\dfrac{\left(x+1\right)^2}{x\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{x\left(x-1\right)}\\ d,=\dfrac{3x+2-12x+8+10x-8}{\left(3x-2\right)\left(3x+2\right)}=\dfrac{x+2}{\left(3x-2\right)\left(3x+2\right)}\\ e,=\dfrac{3x-3+4x^2-2x-4x^2+4}{2x\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{2x\left(x-1\right)\left(x+1\right)}=\dfrac{1}{2x\left(x-1\right)}\)
\(f,=\dfrac{6x^2-6xy-x^2-xy}{10\left(x+y\right)\left(x-y\right)}=\dfrac{5x^2-7xy}{10\left(x-y\right)\left(x+y\right)}\\ g,=\dfrac{4a^2-3a+5+2a^2-a+1-6a^2-6a-6}{\left(a-1\right)\left(a^2+a+1\right)}=\dfrac{-10a}{a^3-1}\\ h,=\dfrac{5x^2-y^2-3x^2+2xy}{xy}=\dfrac{2x^2+2xy-y^2}{xy}\\ i,=\dfrac{x^2+9xy-3xy+9y^2}{x\left(x-3y\right)\left(x+3y\right)}=\dfrac{\left(x+3y\right)^2}{x\left(x-3y\right)\left(x+3y\right)}=\dfrac{x+3y}{x\left(x-3y\right)}\)
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