Using the lens formula:

Using the lenses formula and applying the real-is-positive convention

\(\frac{1}{v}\) + \(\frac{1}{u}\) = \(\frac{1}{f}\)

f = -10cm for diverging lens, v = 5cm real image

\(\frac{1}{u}\) = \(\frac{1}{f}\) - \(\frac{1}{v}\)

 \(\frac{1}{u}\) = \(\frac{1}{-10}\) - \(\frac{1}{5}\) 

 \(\frac{1}{u}\) = \(\frac{-1 - 2}{10}\) = \(\frac{-3}{10}\) 

U = \(\frac{10}{-3}\) = - 3.33cm

The negative sign indicates that the object is on the same side as the incoming light.