Question

trình bày đầy đủ nha

Answer 1

\(\dfrac{x^2-y^2+6x+9}{2x-2y+6}=\dfrac{x^2+6x+9-y^2}{2\left(x-y+3\right)}=\dfrac{\left(x+3\right)^2-y^2}{2\left(x-y+3\right)}=\dfrac{\left(x+3-y\right)\left(x+3+y\right)}{2\left(x-y+3\right)}=\dfrac{x+y+3}{2}\)

\(\dfrac{x^2-2xy+y^2}{x-y}=\dfrac{\left(x-y\right)^2}{x-y}=x-y\)

\(\dfrac{x^2-7x+xy-7y}{x+y}=\dfrac{x\left(x-7\right)+y\left(x-7\right)}{x+y}=\dfrac{\left(x+y\right)\left(x-7\right)}{x+y}=x-7\)