The expression shown in the image is:

$\left( \sqrt{45} - \sqrt{5} \right)^2$

Steps to Simplify:

1. Simplify the square roots:

   • $\sqrt{45} = \sqrt{9 \times 5} = 3\sqrt{5}$
   • $\sqrt{5}$ remains as is.

   So, the expression becomes: $\left( 3\sqrt{5} - \sqrt{5} \right)^2$

2. Factor out the common term $\sqrt{5}$: $\left( 3\sqrt{5} - \sqrt{5} \right) = \sqrt{5}(3 - 1) = 2\sqrt{5}$

   Now the expression is: \