\(=\dfrac{6}{12}+\dfrac{8}{12}+\dfrac{3}{12}\\ =\dfrac{6+8+3}{12}\\ =\dfrac{17}{12}\)

1.

\(\Leftrightarrow10x\left(x-y\right)+8y\left(x-y\right)\\ \Leftrightarrow\left(x-y\right)\left(10x+8y\right)\\ \Leftrightarrow2\left(x-y\right)\left(5x+4y\right)\\ 2.\\ \Leftrightarrow\left(x^2+3xy\right)-\left(5x+15y\right)\\ \Leftrightarrow x\left(x+3y\right)-5\left(x+3y\right)\\ \Leftrightarrow\left(x+3y\right)\left(x-5\right)\)

\((\sqrt(a^(3)b)+\sqrt(ab^(3))-ab)//sqrt(ab)\)

không hiểu lắm;-;