Tia phản xạ quay 1 góc 30 độ

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D=\(\dfrac{2}{xy}:\left(\dfrac{1}{x^2}-\dfrac{2}{xy}+\dfrac{1}{y^2}\right)-\dfrac{x^2+y^2}{\left(x-y\right)^2}\)

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

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

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

D=-1

a 18km/h

b 43,2km/h

c 13.3m/s

d 1,5m/s=5,4

e 17,2m/s=1722,2cm/s